0001514416-21-000092 | 10-K | XBRL Viewer

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Cover - USD ($) $ in Millions	12 Months Ended
Cover - USD ($) $ in Millions	Dec. 31, 2020	Feb. 19, 2021	Jun. 30, 2020
Entity Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-38285
Entity Registrant Name	BANDWIDTH INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	56-2242657
Entity Address, Address Line One	900 Main Campus Drive
Entity Address, City or Town	Raleigh
Entity Address, State or Province	NC
Entity Address, Postal Zip Code	27606
City Area Code	(800)
Local Phone Number	808-5150
Title of 12(b) Security	Class A Common Stock, par value $0.001 per share
Trading Symbol	BAND
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Entity Shell Company	false
Entity Public Float			$ 2,625
Documents Incorporated by Reference	Portions of the registrant’s Definitive Proxy Statement for the 2021 Annual Meeting of Stockholders are incorporated herein by reference in Part II and Part III of this Annual Report on Form 10-K to the extent stated herein. Such Definitive Proxy Statement will be filed with the Securities and Exchange Commission within 120 days of the registrant’s fiscal year ended December 31, 2020.
Entity Central Index Key	0001514416
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Amendment Flag	false
Class A voting common stock
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		22,664,030
Class B voting common stock
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		2,334,058

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 72,163	$ 184,414
Restricted cash	9,274	590
Other investments	40,000	0
Accounts receivable, net of allowance for doubtful accounts	55,243	30,187
Prepaid expenses and other current assets	14,508	9,260
Deferred costs	2,411	2,498
Total current assets	193,599	226,949
Property and equipment, net	51,645	41,654
Operating right-of-use asset, net	19,491	21,031
Intangible assets, net	248,055	6,569
Deferred costs, non-current	3,604	1,952
Other long-term assets	1,975	1,533
Goodwill	372,239	6,867
Deferred tax asset, net	0	34,861
Total assets	890,608	341,416
Current liabilities:
Accounts payable	11,665	4,190
Accrued expenses and other current liabilities	63,065	27,328
Current portion of deferred revenue	6,515	5,177
Advanced billings	5,429	4,167
Operating lease liability, current	5,515	4,876
Total current liabilities	92,189	45,738
Other liabilities	1,707	0
Operating lease liability, net of current portion	17,202	19,868
Deferred revenue, net of current portion	6,386	5,720
Deferred tax liability	61,005	0
Convertible senior notes	282,196	0
Total liabilities	460,685	71,326
Commitments and contingencies
Stockholders’ equity:
Preferred stock; $0.001 par value; 10,000,000 shares authorized; 0 shares issued	0	0
Additional paid-in capital	451,463	275,553
Accumulated deficit	(49,505)	(5,528)
Accumulated other comprehensive income	27,941	41
Total stockholders’ equity	429,923	270,090
Total liabilities and stockholders’ equity	890,608	341,416
Class A voting common stock
Stockholders’ equity:
Class A and Class B common stock	22	19
Class B voting common stock
Stockholders’ equity:
Class A and Class B common stock	$ 2	$ 5

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Preferred stock, par value (in usd per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue	$ 343,113	$ 232,594	$ 204,113
Cost of revenue	185,252	124,959	108,145
Gross profit	157,861	107,635	95,968
Operating expenses:
Research and development	42,059	31,461	20,897
Sales and marketing	40,552	35,020	20,731
General and administrative	88,755	58,847	47,588
Total operating expenses	171,366	125,328	89,216
Operating income (loss)	(13,505)	(17,693)	6,752
Other income (expense), net
Interest income (expense), net	(13,672)	2,446	301
Other income (expense), net		23	0
Other income (expense), net	(1,795)
Total other income (expense)	(15,467)	2,469	301
Income (loss) before income taxes	(28,972)	(15,224)	7,053
Income tax benefit (provision)	(15,005)	17,718	10,870
Net income (loss)	$ (43,977)	$ 2,494	$ 17,923
Net income (loss) per share:
Basic (in dollars per share)	$ (1.83)	$ 0.11	$ 0.96
Diluted (in dollars per share)	$ (1.83)	$ 0.10	$ 0.85
Weighted average number of common shares outstanding:
Basic (in shares)	24,092,574	22,640,461	18,573,067
Diluted (in shares)	24,092,574	23,923,777	21,140,382
CPaaS
Revenue	$ 298,090	$ 197,944	$ 164,415
Cost of revenue	160,706	110,343	94,296
Other
Revenue	45,023	34,650	39,698
Cost of revenue	$ 24,546	$ 14,616	$ 13,849

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (43,977)	$ 2,494	$ 17,923
Other comprehensive (loss) income
Unrealized (loss) gain on marketable securities, net	0	1	(1)
Foreign currency translation, net of income taxes	27,900	41	0
Total other comprehensive (loss) income	27,900	42	(1)
Total comprehensive income (loss)	$ (16,077)	$ 2,536	$ 17,922

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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+ Details

Consolidated Statements of Changes in Stockholders’ Equity - USD ($) $ in Thousands	Total	Adjustment to opening retained earnings due to adoption of ASC 606	Additional paid-in capital	Accumulated other comprehensive (loss) income	Accumulated deficit	Accumulated deficit Adjustment to opening retained earnings due to adoption of ASC 606	Class A voting common stock	Class A voting common stock Common stock	Class A voting common stock Common stock Conversion of Class B voting common stock to Class A voting common stock	Class B voting common stock	Class B voting common stock Common stock	Class B voting common stock Common stock Conversion of Class B voting common stock to Class A voting common stock
Beginning balance (in shares) at Dec. 31, 2017								4,197,831			13,440,725
Beginning balance at Dec. 31, 2017	$ 76,711		$ 102,465	$ 0	$ (25,771)			$ 4			$ 13
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercises of vested stock options (in shares)								1,724,689
Exercises of vested stock options	11,046		11,044					$ 2
Vesting of restricted stock units (in shares)								11,000
Exercise of warrants to purchase common stock (in shares)								48,904
Exercise of warrants to purchase common stock	37		37
Conversion of Class B voting common stock to Class A voting common stock (in shares)								6,929,993			(6,929,993)
Conversion of Class B voting common stock to Class A voting common stock	0							$ 7			$ (7)
Issuance of common stock (in shares)								330
Issuance of common stock	11		11
Costs in connection with public offering	(285)		(285)
Unrealized loss on marketable securities	(1)			(1)
Stock based compensation	3,328		3,328
Net income (loss)	17,923				17,923
Ending balance (in shares) at Dec. 31, 2018								12,912,747			6,510,732
Ending balance at Dec. 31, 2018	108,770	$ (174)	116,600	(1)	(7,848)	$ (174)		$ 13			$ 6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercises of vested stock options (in shares)								1,075,482
Exercises of vested stock options	7,357		7,356					$ 1
Vesting of restricted stock units (in shares)								163,944
Conversion of Class B voting common stock to Class A voting common stock (in shares)									1,583,331			(1,583,331)
Conversion of Class B voting common stock to Class A voting common stock	1								$ 2			$ (1)
Issuance of common stock (in shares)								2,875,000
Issuance of common stock	147,391		147,388					$ 3
Costs in connection with public offering	(834)		(834)
Equity awards withheld for tax liability (in shares)								(26,026)
Equity awards withheld for tax liability	(1,583)		(1,583)
Unrealized loss on marketable securities	1			1
Foreign currency translation	41			41
Stock based compensation	6,626		6,626
Net income (loss)	2,494				2,494
Ending balance (in shares) at Dec. 31, 2019							18,584,478	18,584,478		4,927,401	4,927,401
Ending balance at Dec. 31, 2019	270,090		275,553	41	(5,528)	$ 174		$ 19			$ 5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercises of vested stock options (in shares)								593,084
Exercises of vested stock options	4,076		4,075					$ 1
Vesting of restricted stock units (in shares)								161,067
Conversion of Class B voting common stock to Class A voting common stock (in shares)									2,431,276			(2,431,276)
Conversion of Class B voting common stock to Class A voting common stock	(2)								$ 1			$ (3)
Issuance of debt conversion option	104,553		104,553
Debt conversion option issuance costs, net of tax	(3,742)		(3,742)
Capped call option purchase price	(43,320)		(43,320)
Equity awards withheld for tax liability (in shares)								(20,295)
Equity awards withheld for tax liability	(1,916)		(1,916)
Equity consideration for Voxbone acquisition (in shares)								663,394
Equity consideration for Voxbone acquisition	106,380		106,379					$ 1
Foreign currency translation	27,900			27,900
Stock based compensation	9,881		9,881
Net income (loss)	(43,977)				(43,977)
Ending balance (in shares) at Dec. 31, 2020							22,413,004	22,413,004		2,496,125	2,496,125
Ending balance at Dec. 31, 2020	$ 429,923		$ 451,463	$ 27,941	$ (49,505)			$ 22			$ 2

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities
Net income (loss)	$ (43,977)	$ 2,494	$ 17,923
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities
Depreciation and amortization	16,803	9,538	5,824
Right-of-use asset amortization	4,812	4,269	0
Accretion of bond discount	0	(700)	(164)
Gain on sale of marketable securities	0	(4)	0
Amortization of debt discount and issuance costs	15,647	177	64
Stock-based compensation	9,881	6,626	3,339
Deferred taxes	14,266	(17,502)	(10,833)
Loss on disposal of property and equipment	334	456	191
Changes in operating assets and liabilities:
Accounts receivable, net of allowances	(18,832)	(6,178)	(2,784)
Prepaid expenses and other assets	(2,258)	(4,176)	(1,926)
Deferred costs	(1,565)	(69)	243
Accounts payable	315	1,145	(169)
Accrued expenses and other liabilities	11,548	5,474	4,826
Deferred revenue and advanced billings	2,845	554	6,019
Operating right-of-use liability	(5,301)	(3,357)	0
Deferred rent	0	0	2,080
Net cash provided by (used in) operating activities	4,518	(1,253)	24,633
Cash flows from investing activities
Purchase of property and equipment	(12,273)	(22,215)	(12,419)
Capitalized software development costs	(2,319)	(3,544)	(2,028)
Purchase of marketable securities	0	(68,361)	(35,236)
Proceeds from sales and maturities of marketable securities	0	86,467	18,000
Purchase of other investments	(230,780)	0	0
Proceeds from sales and maturities of other investments	190,780	0	0
Acquisition, net of cash acquired	(400,493)	0	0
Net cash used in investing activities	(455,085)	(7,653)	(31,683)
Cash flows from financing activities
Payments on finance leases	(28)	0	(92)
Payment of costs related to offering	0	(757)	0
Proceeds from the follow-on public offering, net of underwriting discounts	0	147,391	0
Proceeds from issuance of convertible senior notes	400,000	0	0
Payment of debt issuance costs	(11,990)	(167)	(25)
Purchase of capped call	(43,320)	0	0
Proceeds from exercises of stock options	4,073	7,357	11,046
Proceeds from exercises of warrants	0	0	37
Value of equity awards withheld for tax liabilities	(1,844)	(1,406)	0
Net cash provided by financing activities	346,891	152,418	10,681
Effect of exchange rate changes on cash, cash equivalents and restricted cash	109	(9)	0
Net increase (decrease) in cash, cash equivalents, and restricted cash	(103,567)	143,503	3,631
Cash, cash equivalents, and restricted cash, beginning of period	185,004	41,501	37,870
Cash, cash equivalents, and restricted cash, end of period	81,437	185,004	41,501
Supplemental disclosure of cash flow information
Cash paid for interest	579	341	107
Cash paid (refunded) for taxes	454	(178)	155
Right-of-use assets obtained in exchange for new operating lease liabilities	3,105	4,528	0
Property and equipment obtained in exchange for new finance lease liabilities	462	0	0
Supplemental disclosure of noncash investing and financing activities
Purchase of property and equipment, accrued but not paid	6,043	1,375	1,204
Value of common stock issued in acquisition	106,379	0	0
Acquisition holdback	8,595	0	0
Equity awards withheld for tax liabilities, accrued but not paid	247	177	0
Acquisition of equipment through finance leases	113	0	0
IPO
Cash flows from financing activities
Payment of costs related to offering	$ 0	$ 0	$ (285)

Organization and Description of Business	12 Months Ended
Organization and Description of Business	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of Business	1. Organization and Description of Business Bandwidth Inc. (together with its subsidiaries, “Bandwidth” or the “Company”) was founded in July 2000 and incorporated in Delaware on March 29, 2001. The Company’s headquarters are located in Raleigh, North Carolina. The Company is an international cloud-based, software-powered communications platform-as-a-service (“CPaaS”) provider that enables enterprises to create, scale and operate voice or messaging communications services across any mobile application or connected device. The Company has two operating and reportable segments, CPaaS and Other. CPaaS revenue is derived from usage and monthly services fees charged for usage of Voice, Messaging, 911 and Phone Numbers solutions through the Company’s proprietary CPaaS software application programming interfaces. Other revenue consists of fees charged for services provided such as: SIP trunking, data resale, and a hosted Voice-over Internet Protocol (“VoIP”). The Other segment also includes revenue from traffic generated by other carriers, SMS registration fees and other miscellaneous product lines. On November 2, 2020, Bandwidth completed the acquisition (the “Business Combination” or the “Transaction”) of Voxbone S.A., a private limited liability company registered under the laws of Belgium, pursuant to the Share Purchase Agreement (“SPA”) dated as of October 12, 2020, in which Bandwidth agreed to acquire all of the A Ordinary Shares, B Ordinary Shares and C Ordinary Shares of Voice Topco Limited (“Voice Topco”). Voice Topco directly or indirectly held all of the issued and outstanding shares of Voxbone, S.A., which is the operating subsidiary of Voice Topco. Voice Topco and its subsidiaries are collectively referred to “Voxbone” herein. Upon closing of the Transaction, Bandwidth paid cash consideration in Euros equivalent to $413,005 in US dollars, which included a holdback amount of $8,153 (the “Holdback”), and issued 663,394 Class A common shares at $160.355 per share for the purchase of Voxbone. Bandwidth’s management has concluded that the acquired assets and assumed liabilities of Voxbone, together with acquired processes and employees, represent a business as defined in the Financial Accounting Standards Board's (“FASB”) Accounting Standards Codification (“ASC”) 805, Business Combinations. Accordingly, the Transaction has been accounted for as a Business Combination, with Voxbone as a wholly owned subsidiary of Bandwidth. See Note 3, “Business Combination” to these consolidated financial statements, for additional details.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Basis of Presentation

The consolidated financial statements and accompanying notes were prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”).

Reclassification

The Company reclassified certain prior year amounts to conform to the current year presentation. These reclassifications had no impact on the previously reported total assets, liabilities, stockholder’s deficit or net income.

Principles of Consolidation

The consolidated financial statements include the accounts of Bandwidth Inc. and its wholly owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation.

Use of Estimates

The preparation of the Company’s consolidated financial statements in conformity with GAAP requires the Company to make estimates and judgments that affect the amounts reported in these financial statements and accompanying notes. These estimates in the consolidated financial statements include, but are not limited to, allowance for doubtful accounts, reserve for expected credit losses, reserve for sales credits, recoverability of long lived and intangible assets, fair value of acquired intangible assets and goodwill, discount rates used in the valuation of right-of-use assets and lease liabilities, the fair value of the liability and equity components of the Company’s Convertible Notes (as defined herein), estimated period of benefit, valuation allowances on deferred tax assets, certain accrued expenses and contingencies, economic and demographic actuarial assumptions related to pension and other postretirement benefit costs and liabilities, estimated cash flows on asset retirement obligation. Although the Company believes that the estimates it uses are reasonable, due to the inherent uncertainty involved in making these estimates, actual results reported in future periods could differ from those estimates.

Effective January 1, 2020, due to the continued growth in customers and low churn rates, the Company updated its calculation of the estimated period of benefit for nonrefundable upfront fees from 3 to 4 years. For the year ended December 31, 2020 the Company reduced total revenue by approximately $1,632 and reduced cost of revenue by approximately $859, related to the change in the estimated period of benefit.

Effective July 1, 2020, due to significant investment in software during the first half of 2020 and management's expectation that such investment would yield benefit for a longer period of time, the Company updated its estimated useful life for internal-use software development from 3 to 4 years. For the year ended December 31, 2020, the Company reduced cost of revenue by $314 and general and administrative expense by $104.

Revenue Recognition

Adoption of Accounting Standards Codification (“ASC”) 606, “Revenue from Contracts with Customers”

On January 1, 2019, the Company adopted the guidance of ASC 606, Revenue from Contracts with Customers, using the modified retrospective method applied to those contracts which were not completed as of January 1, 2019. The Company’s results for reporting periods beginning after January 1, 2019 are presented in accordance with the provisions under ASC 606 and prior period amounts have not been adjusted and continue to be reported in accordance with the Company’s revenue recognition policy as further described in Note 2, Summary of Significant Accounting Policies, to its Annual Report on Form 10-K for the year ended December 31, 2018.

In connection with the adoption of ASC 606, the Company recognized a net increase to its opening accumulated deficit of $174 as of January 1, 2019, related to a discount present in one of its contracts.

Prior to the adoption of ASC 606, the Company recognized the majority of its revenue based on the usage of its customers in the period the traffic traversed the Company’s network. The Company determined that ASC 606 continues to support the recognition of revenue over time for the majority of the Company’s contracts due to the continuous transfer of control to the customer.

The adoption of ASC 606 did not result in a change in the Company’s accounting for its commission costs, which will continue to be expensed as incurred. The Company pays commissions over time and a corresponding requisite substantive service condition exists for the employee to receive the commission. The Company determined the timing of the commission payments and the underlying service performed by the employee were commensurate.

The impact on the Company’s balance sheet presentation includes separately presenting customer refundable prepayments as advanced billings, whereas under ASC 605 these were included in the current portion of deferred revenue and advanced billings.

Revenue Recognition Policy

Revenue recognition commences upon transfer of control of promised goods or services to customers in an amount that the Company expects to receive in exchange for those products or services.

The Company determines revenue recognition through the following steps:

•identification of the contract, or contracts, with a customer;

•identification of the performance obligations in the contract;

•determination of the transaction price;

•allocation of the transaction price to the performance obligations in the contract; and

•recognition of revenue, when, or as, the Company satisfies a performance obligation.

Nature of Products and Services

Revenue consists primarily of the sale of communications services offered through Application Programming Interface (“API”) software solutions to large enterprise, as well as small and medium-sized business, customers and is generally derived from usage and service fees in both the CPaaS and Other segments. Usage revenue includes voice communication (primarily driven by inbound minutes, outbound minutes and toll-free minutes) and messaging communication (driven by the number of messages) that traverse the platform and network. Service fees include the provision and management of phone numbers and emergency services access.

The majority of the Company’s revenue is generated from usage-based fees earned from customers accessing the Company’s communications platform. Access to the Company’s communication platform is considered a series of distinct services, with continuous transfer of control to the customer, comprising one performance obligation and usage-based fees are recognized in revenue in the period the traffic traverses the Company’s network. For the years ended December 31, 2018, 2019 and 2020 the revenue from usage-based fees represented $105,481, $131,626 and $219,817 of CPaaS revenue, respectively, and $32,524, $29,012 and $40,842 of Other revenue, respectively.

Revenue from service fees is recognized on a ratable basis as the service is provided, which is typically one month. For the years ended December 31, 2018, 2019 and 2020 the revenue from service fees represented $55,719, $61,193 and $72,256 of CPaaS revenue, respectively, and $7,174, $5,638 and $4,181 of Other revenue, respectively.

The remaining $3,215, $5,125 and $6,017 of CPaaS revenue for the years ended December 31, 2018, 2019 and 2020 respectively, are generated from other miscellaneous services.

Infrequently, Bandwidth’s contracts with customers may include multiple performance obligations. For such arrangements, revenues are allocated to each performance obligation based on its relative standalone selling price. Generally, standalone selling prices are determined based on the prices charged to similar customers for similar services.

When required as part of providing service, revenues and associated expenses related to nonrefundable, upfront service activation and setup fees are deferred and recognized over the longer of the associated service contract period or estimated customer life.

The Company’s contracts do not contain general rights of return. However, occasionally credits may be issued. The Company’s contracts do not provide customers with the right to take possession of the software supporting the applications. Amounts that have been invoiced are recorded in accounts receivable and in revenue or deferred revenue depending on whether the revenue recognition criteria have been met.

The Company maintains a reserve for sales credits. Credits are accounted for as variable consideration and are estimated based on several inputs including historical experience and current trends of credit issuances. Adjustments to the reserve are recorded against revenue.

The Company has various sales commission plans for which eligible employees can earn commissions from the sale of products and services to customers. Eligible employees must be employed at the time of payment in order to receive a commission. The Company pays commissions over time and a corresponding requisite substantive service condition exists for the employee to receive the commission. The Company determined that the timing of the commission payments and the underlying service performed by the employee were commensurate. Accordingly, sales commissions are generally expensed as incurred. These costs are recorded within sales and marketing expenses.

Contract Assets and Liabilities

The following table provides information about receivables and contract liabilities from contracts with customers:


	As of December 31,
	2019		2020
Receivables (1)	$	30,187	$	55,243
Contract liabilities (2)	10,897		12,901

________________________

(1) Included in accounts receivable, net of allowance for doubtful accounts on the consolidated balance sheet.

(2) Included in current portion of deferred revenue and deferred revenue, net of current portion on the consolidated balance sheet.

Deferred revenue is recorded when cash payments are received in advance of future usage on contracts. Revenue is typically recognized in the following month when service is rendered or, in the case of nonrefundable upfront fees, over the estimated period of benefit. Customer refundable payments are recorded as advanced billings. During the year ended December 31, 2020, the Company recognized revenue of $3,599 related to contract liabilities recorded at the beginning of the year. The Company expects to recognize $6,515 in revenue over the next twelve months related to its contract liabilities as of December 31, 2020.

Cost of Revenue

CPaaS cost of revenue consists primarily of fees paid to other network service providers from whom the Company buys services such as minutes of use, phone numbers, messages, porting of customer numbers, and network circuits. Cost of revenue also contains costs related to the support of the network, web services and cloud infrastructure, capacity planning and management, rent for network facilities, software licenses, hardware and software maintenance fees, and network engineering services. Personnel costs (including non-cash stock-based compensation expenses) associated with personnel who are responsible for the delivery of services, operation and maintenance of the communications network, customer support, as well as, third party support agreements, and depreciation and amortization of acquired technology intangibles are also recorded as cost of revenue.

Other cost of revenue consists of amortization of capital software development costs related to platform applications supporting non-CPaaS services including circuit costs paid to third party providers, internet connectivity expenses, minutes of use, contractors, regulatory fees and surcharges, depreciation, and software and hardware maintenance fees.

Operating Expenses

Research and Development

Research and development expenses consist primarily of personnel costs (including non-cash stock-based compensation expenses), outsourced software development and engineering services and cloud infrastructure fees for staging and development outsourced engineering services.

Sales and Marketing

Sales and marketing expenses consist primarily of personnel costs, including commissions for sales employees and non-cash stock-based compensation expenses. Sales and marketing expenses also include expenditures related to advertising, marketing, brand awareness activities, sales support and professional services fees.

General and Administrative

General and administrative expenses consist primarily of personnel costs for support personnel and executives in accounting, finance, legal, information services, human resources and administrative functions. General and administrative expenses also include costs related to product management and reporting, data services, customer billing and collection functions, and other professional services fees, credit card processing fees, rent associated with the Company’s headquarters in Raleigh, North Carolina and its offices worldwide, depreciation and amortization.

Cash and Cash Equivalents

The Company classifies all highly liquid investments with original stated maturities of three months or less from the date of purchase as cash equivalents and all highly liquid investments with original stated maturities of greater than three months from the date of purchase as current marketable securities, with the exception of time deposits which are classified as other investments. Cash deposits are primarily in financial institutions in the United States. However, cash for monthly operating costs of international operations are deposited in banks outside the United States. The Company has a policy of making investments only with commercial institutions that have at least an investment grade credit rating. The Company invests its cash primarily in government securities and obligations, corporate debt securities, money market funds and reverse repurchase agreements (“RRAs”). RRAs are collateralized by deposits in the form of Government Securities and Obligations for an amount not less than 102% of their value. The Company does not record an asset or liability as the Company is not permitted to sell or repledge the associated collateral. The Company has a policy that the collateral has at least an “A” (or equivalent) credit rating. The Company utilizes a third-party custodian to manage the exchange of funds and ensure that collateral received is maintained at 102% of the value of the RRAs on a daily basis. RRAs with stated maturities of greater than three months from the date of purchase are classified as marketable securities.

Restricted Cash

Restricted cash consists primarily of the Holdback remaining to be paid to the Selling Stockholders of Voxbone, employee withholding tax liability and employee benefits contributions not yet remitted. The Company has classified this asset as a short-term asset in order to match the expected period of restriction.

Accounts Receivable and Current Expected Credit Losses

Accounts receivable are stated at realizable value, net of allowances, which includes an allowance for doubtful accounts and a reserve for expected credit losses. The allowance for doubtful accounts is based on management’s assessment of the collectability of its customer accounts. The Company regularly reviews the composition of the accounts receivable aging, historical bad debts, changes in payment patterns, customer creditworthiness, current economic trends, and reasonable and supportable forecasts about the future. Relevant risk characteristics include customer size and historical loss patterns. Management has evaluated the expected credit losses related to trade accounts receivable and determined that allowances of approximately $769 and $1,203 for uncollectible accounts and customer balances that are disputed were required as of December 31, 2019 and December 31, 2020, respectively. Refer to Note 5, “Financial Statement Components” to these consolidated financial statements, for a rollforward of the components of the allowances as of December 31, 2019 and December

The Company includes unbilled receivables in its accounts receivable balance. Generally, these receivables represent services provided to customers, which will be billed in the next billing cycle. All amounts are considered collectible and billable. As of December 31, 2019 and December 31, 2020, unbilled receivables were $16,200 and $27,692, respectively.

Concentration of Credit Risk

Financial instruments that are exposed to concentration of credit risk consist primarily of cash and cash equivalents, marketable securities, other investments and trade accounts receivable. Cash deposits may be in excess of insured limits. The Company believes that the financial institutions that hold its cash deposits are financially sound and, accordingly, minimal credit risk exists with respect to these balances.

With regard to customers, credit evaluation and account monitoring procedures are used to minimize the risk of loss. The Company believes that no additional credit risk beyond amounts provided for by the allowance for doubtful accounts are inherent in accounts receivable. As of December 31, 2019, no individual customer represented more than 10% of the Company’s accounts receivable, net of allowance for doubtful accounts. As of December 31, 2020, one individual customer represented approximately 11% of the Company’s accounts receivable, net of allowance for doubtful accounts.

For the years ended December 31, 2018, 2019 and 2020, no individual customer represented more than 10% of the Company’s total revenue.

Property and Equipment, net

Property and equipment, net is stated at cost, less accumulated depreciation and amortization. Depreciation and amortization is calculated on a straight-line basis over the estimated useful lives of those assets as follows:


Computer hardware and software			1 to 7 years
Internal-use software development costs			4 to 7 years
Furniture and fixtures			2 to 5 years
Leasehold improvements			Shorter of the estimated lease term or 4 to 7 years

Maintenance and repairs are charged to expense as incurred.

Deferred Costs

The Company defers certain direct and incremental upfront costs related to the generation of a revenue stream or obtaining a new customer agreement. These costs include installment fees, activation and other telecommunication fees. The Company capitalizes these costs and amortizes them over the longer of the term of the customer contract or the estimated period of benefit, which is approximately four years.

Internal-Use Software Development Costs

Internal-use software includes software that has been acquired, internally developed, or modified exclusively to meet the Company’s needs. The Company capitalizes qualifying internal-use software development costs that are incurred during the application development stage. Capitalization of costs begins when two criteria are met: (i) the preliminary project stage is completed, and (ii) it is probable that the software will be completed and used for its intended function. Capitalization ceases when the software is substantially complete and ready for its intended use, including the completion of all significant testing. The Company also capitalizes costs related to specific upgrades and enhancements when the expenditures will result in additional functionality, and expenses

costs incurred for maintenance and minor upgrades and enhancements. Costs related to preliminary project activities and post-implementation operating activities are expensed as incurred.

Capitalized costs of platform and other software applications are included in property and equipment. These costs are amortized over the estimated useful life of the software on a straight-line basis over four to seven years. Management evaluates the useful life of these assets on an annual basis and tests for impairment whenever events or changes in circumstances occur that could impact the recoverability of these assets.

Debt Issuance Costs

The Company incurred debt issuance costs associated with obtaining and entering into credit agreements. These costs customarily include non-refundable structuring fees, commitment fees, up-front fees and syndication expenses. The Company has a policy to defer and amortize these costs based on the effective interest method over the term of the credit agreements.

Goodwill

The Company reviews goodwill and indefinite-lived intangible assets at least annually, as of December 31, for possible impairment. Goodwill and indefinite-lived intangible assets are reviewed for possible impairment at an interim date if an event occurs or circumstances change that would more likely than not reduce the fair value of the reporting unit or indefinite-lived intangible asset below its carrying value. The Company tests goodwill at the reporting unit level and has determined that it has 2-reporting units, CPaaS and Other. All Goodwill is allocated to the CPaaS reporting unit. Management may first evaluate qualitative factors to assess if it is more likely than not that the fair value of a reporting unit is less than its carrying amount and to determine if a two-step impairment test is necessary. Management may choose to proceed directly to the two-step evaluation, bypassing the initial qualitative assessment. The first step of the impairment test involves comparing the fair value of the reporting unit to its net book value, including goodwill. If the carrying value exceeds its fair value, then the Company would perform the second step of the goodwill impairment test to determine the amount of the impairment loss. The impairment loss would be calculated by comparing the implied fair value of the goodwill to its carrying value. In calculating the implied fair value of goodwill, the fair value of the entity would be allocated to all of the other assets and liabilities based on their fair values. The excess of the fair value of the entity over the amount assigned to other assets and liabilities is the implied fair value of goodwill. An impairment loss would be recognized when the carrying amount of goodwill exceeds its implied fair value.

The Company makes assumptions regarding estimated future cash flows, discount rates, long-term growth rates and market values to determine each reporting unit’s and indefinite-lived intangible asset’s estimated fair value. If these estimates or related assumptions change in the future, the Company may be required to record an impairment charge. As of December 31, 2019 and 2020, the Company has recorded goodwill of $6,867 and $372,239, respectively. No goodwill impairment charges were recorded for the years ended December 31, 2018, 2019 and 2020.

Impairment of Long-Lived Assets

The Company evaluates long-lived assets, including property and equipment and definite lived intangible assets, for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets held and used is measured by a comparison of the carrying amount of an asset or an asset group to estimated undiscounted future net cash flows expected to be generated by the asset or asset group. If such evaluation indicates that the carrying amount of the asset or the asset group is not recoverable, any impairment loss would be equal to the amount the carrying value exceeds the fair value.

Business Combinations

The Company uses the acquisition method of accounting for business combinations which requires the tangible and intangible assets acquired and liabilities assumed to be recorded at their respective fair market value as

of the acquisition date. Goodwill represents the excess of the consideration transferred over the fair value of the net assets acquired. The fair values of the assets acquired and liabilities assumed are determined based upon the Company’s valuation and involves making significant estimates and assumptions based on facts and circumstances that existed as of the acquisition date. The Company uses a measurement period following the acquisition date to gather information that existed as of the acquisition date that is needed to determine the fair value of the assets acquired and liabilities assumed. The measurement period ends once all information is obtained, but no later than one year from the acquisition date.

Advertising Costs

The Company expenses advertising costs as incurred. Advertising costs totaled $953, $1,528 and $1,617 for the years ended December 31, 2018, 2019 and 2020, respectively, which are included in sales and marketing expenses in the accompanying consolidated statements of operations.

Commissions

Commissions consist of variable compensation earned by sales personnel and third-party resellers. Sales commissions associated with the acquisition of a new customer contract are paid over time, based on monthly revenues, and are recognized as sales and marketing expense in the period incurred.

Stock-Based Compensation

The Company accounts for stock-based compensation expense related to all stock-based awards based on the fair value of the award on the grant date. Stock-based compensation expense is recognized on a straight-line basis over the requisite service period, which is generally four years. The fair value of the restricted stock units is determined using the fair value of the Company’s Class A common stock on the date of grant. The Company uses the Black-Scholes option pricing model, net of estimated forfeitures, to measure the fair value of its stock options.

The Company has elected to estimate expected forfeitures, and, as such, the Company must also determine a forfeiture rate to calculate the stock-based compensation for awards. Through December 31, 2020, the Company recognized compensation for only the portion of options expected to vest using an estimated forfeiture rate that was derived from historical employee termination behavior. If any of the assumptions used in the Black-Scholes option pricing model change, stock-based compensation for future options may differ materially compared to that associated with previous grants.

Income Taxes

The Company accounts for income taxes under the asset and liability method. Under this method, deferred tax assets and liabilities are determined based on temporary differences between the financial statement and tax basis of assets and liabilities using enacted tax rates. The Company recognizes the effect of a change in tax rates on deferred tax assets and liabilities in the period that includes the enactment date.

The Company reduces the measurement of a deferred tax asset, if necessary, by a valuation allowance if it is more likely than not that it will not realize some or all the deferred tax asset. Quarterly, the Company reviews the deferred tax assets for recoverability based on historical taxable income, projected future taxable income, the expected timing of the reversals of existing temporary differences and the implementation of prudent and feasible tax planning strategies. The evaluation of the recoverability of deferred tax assets requires judgment in assessing future profitability. Should there be a change in the ability to recover deferred tax assets, the Company’s income tax provision would increase or decrease in the period in which the assessment is changed.

The Company accounts for uncertain tax positions by recognizing the financial statement effects of a tax position only when, based upon technical merits, it is more likely than not that the position will be sustained upon examination. The tax benefit recognized is measured as the largest amount of benefit determined on a cumulative probability basis that the Company believes is more likely than not to be realized upon ultimate settlement of the

position. The Company recognizes potential accrued interest and penalties associated with unrecognized tax positions in income tax expense.

Operating Segments

Operating segments are defined as components of an enterprise for which separate financial information is available and evaluated regularly by the chief operating decision maker (“CODM”) in deciding how to make operating decisions, allocate resources and in assessing performance. The Company has two operating segments, CPaaS and Other, which are deemed to be reportable segments. The Company’s CODM is its Chief Executive Officer. The CODM evaluates the performance of the Company’s operating segments primarily based on revenue and gross profit. The Company does not analyze discrete segment balance sheet information related to long-term assets. All other financial information is evaluated on a consolidated basis.

Earnings per Share

Basic earnings per share attributable to common stockholders is calculated by dividing the net income attributable to common stockholders by the weighted-average number of shares of common stock outstanding for the period.

Diluted net income per share is calculated by giving effect to all potentially dilutive common stock when determining the weighted-average number of common shares outstanding. For purposes of the diluted net income (loss) per share calculation, options and warrants to purchase common stock and redeemable convertible preferred stock are considered to be potential common stock.

Historically, the Company issued securities other than common stock that participated in dividends (“Participating Securities”). These Participating Securities included the Series A redeemable convertible preferred stock. On November 9, 2017, the Participating Securities were converted to Class B common stock immediately prior to the IPO.

Foreign currency translation

The Company has foreign operations with non-USD functional currencies. The Euro and British Pound are the functional currencies for the Company’s international operations.

All of the assets and liabilities of these subsidiaries are converted to U.S. dollars at the exchange rate in effect at the balance sheet date, and equity accounts are carried at historical exchange rates. Revenue and expenses are translated at average exchange rates in effect during each reporting period. Income and expense items are translated at average rates for the period. The net effect of foreign currency translation adjustments is included in shareholder's equity as a component of "Accumulated other comprehensive loss" line item in the accompanying consolidated balance sheets.

Foreign currency transaction gains and losses are the result of exchange rate changes during the period of time between the consummation and cash settlement of transactions denominated in currencies other than the functional currency. Foreign currency transaction gains and losses are recognized in current period earnings as incurred.

Foreign exchange gains and losses, which result from the process of remeasuring foreign currency transactions into the appropriate functional currency, are included in other income, net in the Company’s consolidated statements of operations. The Company recorded $0, $9, $32 in related gains during the years ended December 31, 2018, 2019 and 2020.

Fair Value of Financial Instruments

The carrying amounts of cash and cash equivalents, marketable securities, accounts receivable, accounts payable and accrued expenses approximate fair value as of December 31, 2019 and December 31, 2020 because of

the relatively short duration of these instruments. Marketable securities consist of U.S. treasury securities not otherwise classified as cash equivalents. All marketable securities are considered to be available-for-sale and are recorded at their estimated fair values. Unrealized gains and losses for available-for-sale securities are recorded in other comprehensive (loss) income.

The Company minimizes its credit risk associated with investments by investing primarily in investment grade, liquid securities. The Company policy is designed to preserve capital, maintain liquidity and minimize credit risk, and the policy limits exposure to any one issuer and also establishes minimum credit ratings of approved investments. Periodic evaluations of relative credit standing of those issuers are considered in the Company's investment strategy.

The Company uses a three-tier fair value hierarchy to classify and disclose all assets and liabilities measured at fair value on a recurring basis, as well as assets and liabilities measured at fair value on a non-recurring basis, in periods subsequent to their initial measurement. The hierarchy requires use of observable inputs when available, and to minimize the use of unobservable inputs when determining fair value. The three tiers are defined as follows:

•Level 1. Observable inputs based on unadjusted quoted prices in active markets for identical assets or liabilities;

•Level 2. Inputs, other than quoted prices in active markets, that are observable either directly or indirectly; and

•Level 3. Unobservable inputs for which there is little or no market data, which requires the Company to develop its own assumptions.

A financial instrument’s categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement.

Comprehensive Income (Loss)

The Company has elected to present Comprehensive Income (Loss) and its components as a separate financial statement. Comprehensive income refers to net income and other revenue, expenses, gains and losses that, under generally accepted accounting principles, are recorded as an element of stockholders’ equity but are excluded from the calculation of net income.

Recently Adopted Accounting Standards

In August 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract. This standard aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. ASU 2018-15 is effective for interim and annual reporting periods beginning after December 15, 2019. As a result of the Company’s prospective adoption of this standard, the Company capitalized implementation costs related to cloud computing arrangements of $572 as of December 31, 2020. See Note 7, “Property and Equipment” to these consolidated financial statements, for additional details.

In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement, which eliminates certain disclosure requirements for fair value measurements for all entities, requires public entities to disclose certain new information and modifies some disclosure requirements. ASU 2018-13 is effective for interim and annual reporting periods beginning after December 15, 2019 and for interim periods within those fiscal years. The adoption of this standard did not have a material impact on the Company’s financial statements.

In January 2017, the FASB issued ASU 2017-04, Simplifying the Test for Goodwill Impairment, which simplifies the accounting for goodwill impairment. The ASU removes the second step of the goodwill impairment test that requires a hypothetical purchase price allocation. A goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. ASU 2017-04 is effective for interim and annual reporting periods beginning after December 15, 2019. The adoption of this standard did not have a material impact on the Company’s financial statements.

In June 2016, the FASB issued ASU 2016-13, Financial Instruments–Credit Losses: Measurement of Credit Losses on Financial Instruments, which changes the impairment model for most financial assets. The new model uses a forward-looking expected loss method, which will generally result in earlier recognition of allowances for losses. In November 2018, the FASB issued ASU 2018-19, Codification Improvements to Topic 326, Financial Instruments – Credit Losses, which clarifies that receivables arising from operating leases are not within the scope of Topic 326, Financial Instruments – Credit Losses. Instead, impairment of receivables arising from operating leases should be accounted for in accordance with Topic 842, Leases. In April 2019, the FASB issued ASU 2019-04, Codification Improvements to Topic 326, Financial Instruments—Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments, which clarifies how to apply certain aspects of the new credit losses standard. In November 2019, the FASB issued ASU 2019-10, Financial Instruments—Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842): Effective Dates, which amends certain effective dates for the new standard. In November 2019, the FASB issued ASU 2019-11, Codification Improvements to Topic 326, Financial Instruments—Credit Losses, which clarifies how to apply certain aspects of the new credit losses standard. The accounting standard is effective for annual and interim periods beginning after December 15, 2019. The Company adopted this standard for financial assets measured at amortized cost, including trade receivables. Results for the reporting periods beginning after January 1, 2020 are presented under ASC 326, while prior period amounts continue to be reported in accordance with previously applicable GAAP. The adoption of this standard did not have a material impact on the Company’s financial statements.

Recent Accounting Pronouncements Not Yet Adopted

In October 2020, the FASB issued ASU 2020-10, Codification Improvements, which is intended to address suggestions received from stakeholders on the Accounting Standards Codification and to make other incremental improvements to GAAP. The FASB's intentions for this update is to clarify the codification or correct unintended application of guidance and is not expected to result in a significant change in practice. Amendments include removal of certain references in concept statements, simplification to wording, and the addition of all disclosure-related guidance in the disclosure sections of the codification. The amendments in this update do not change GAAP and transition guidance is primarily for entities that may have applied guidance being amended in an inconsistent manner. This update is effective for annual periods beginning after December 15, 2020, for public business entities. The Company is evaluating the effect of this update on its financial statements.

In August 2020, the FASB issued ASU 2020-06, Debt - Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging - Contracts in Entity's Own Equity (Subtopic 815-40), which is intended to address issues identified as a result of the complexity associated with applying GAAP for certain financial instruments with characteristics of liabilities and equity. For convertible instruments, ASU 2020-06 reduces the number of accounting models for convertible debt instruments and convertible preferred stock, and enhances information transparency by making targeted improvements to the disclosures for convertible instruments and earnings-per-share (EPS) guidance on the basis of feedback from financial statement users. ASU 2020-06 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2021. Early adoption is permitted, but no earlier than fiscal years beginning after December 15, 2020, including interim periods within those fiscal years. The Company is evaluating the effect of adopting this new accounting guidance on its financial statements but does not intend to early adopt.

In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, which is intended to simplify various aspects related to accounting for income taxes. ASU 2019-12 removes certain exceptions to the general principles in Topic 740 and also clarifies and amends existing

guidance to improve consistent application. ASU 2019-12 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. Early adoption is permitted, including adoption in an interim period. The Company is evaluating the effect of adopting this new accounting guidance, but does not expect adoption will have a material impact on its financial statements.

Business Combination

12 Months Ended

Dec. 31, 2020

Business Combinations [Abstract]

Business Combination

3. Business Combination

Voxbone Acquisition

On November 2, 2020, the Company completed the acquisition of Voxbone for total estimated purchase consideration of approximately $519,384, consisting of cash and 663,394 shares of Bandwidth’s Class A common stock. The total estimated purchase consideration is subject to adjustment upon finalization of the net working capital adjustment. Voxbone is an international enterprise cloud communications leader with European-based communications platform and IP voice network. With a global network and extensive regulatory expertise, Voxbone is a national operator in markets around the world, with coverage across 93% of the world by GDP. The Company acquired Voxbone to accelerate its international strategy by several years, giving the company a footprint in 60+ countries.

The purchase consideration exchanged to consummate the acquisition reflects the fair value of the Company's shares issued and the cash paid to the holders of Voxbone’s equity. The fair value of the shares is based on the final closing price of shares of Bandwidth Class A common stock prior to the effective time of the acquisition, which was $160.355 per share, determined as of October 30, 2020.

Preliminary Purchase Price Allocation

For purposes of accounting for the acquisition, the Company was determined to be the accounting acquirer. The Company applied the acquisition method of accounting with respect to the identifiable assets and liabilities of Voxbone, which have been measured at their estimated fair value as of the date of the business combination. Estimates of the fair value of Voxbone’s assets represent management’s best estimate of assumptions about future events and uncertainties, including significant judgments related to future cash flows, discount rates, competitive trends, margin and revenue growth assumptions, royalty rate, customer attrition rates, market comparables, and others, as applicable. Inputs used were generally obtained from historical data, supplemented by current and anticipated market conditions and growth rates.

The following table summarizes the preliminary allocation of purchase price to the identifiable assets acquired and liabilities assumed by Bandwidth, with the excess of purchase price over the fair value of Voxbone’s net assets recorded as goodwill. Due to the timing and the magnitude of the transaction and the multi-jurisdictional nature of the net assets acquired, initial accounting for the acquisition is not complete, and further measurement period adjustments may occur in fiscal year 2021. The Company has estimated the preliminary fair value of net assets acquired based on information currently available and will continue to adjust those estimates as additional information becomes available, including the refinement of market participant assumptions and finalization of tax returns in the pre-acquisition period. The Company will reflect measurement period adjustments in the period in which the adjustments are determined.

The aggregate purchase consideration has been preliminarily allocated as follows:


	Estimated fair value
Purchase Price:
Fair value of cash paid (1)	$	413,005
Fair value of Bandwidth common stock issued	106,379
Total purchase consideration	$	519,384

________________________

(1) Amount subject to adjustment upon finalization of the net working capital adjustment.


	Estimated fair value
Purchase Price Allocation:
Cash	$	4,360
Accounts receivable	5,873
Other current assets	3,315
Property and equipment	3,865
Intangible assets	232,600
Other non-current assets	3,418
Total current liabilities	(17,581)
Deferred tax liability	(58,149)
Other non-current liabilities	(4,881)
Net identifiable assets acquired	172,820
Goodwill	346,564
Net assets acquired	$	519,384

Identifiable intangible assets

The estimated preliminary fair value and weighted average useful life of the Voxbone identifiable intangible assets are as follows.


	Fair value		Weighted average useful life
			(In years)
Developed technology	$	84,100	10
Customer relationships	148,500		15
Preliminary fair value of identifiable intangible assets	$	232,600

Developed technology represents certain proprietary technology that Voxbone uses to deliver its services. Preliminary fair values were determined using a relief from royalty methodology, which estimates the cost savings generated by a company based upon the ownership of an asset for which it would otherwise have had to pay royalties or license fees on revenues earned through the use of the asset. The discount rate used was determined at the time of measurement based on an analysis of the implied internal rate of return of the transaction, weighted average cost of capital and weighted average return on assets. The economic useful life was determined based on the technology cycle related to each developed technology, as well as the cash flows over the forecast period.

Customer relationships represent the preliminary fair value of existing relationships with the Voxbone customers. The preliminary fair value of customer relationships was determined using the Multi-Period Excess Earning Method, which involves isolating the net earnings attributable to the asset being measured based on the present value of the incremental after-tax cash flows (excess earnings) attributable solely to the intangible asset over its remaining useful life. The valuation includes the valuation of the assembled workforce, using the Cost Approach, for purposes of calculating contributory asset charges to be used in the Multi-Period Excess Earning Method valuations. The economic useful life was determined based on historical customer attrition rates.

The Company believes that the amounts of purchased intangible assets recorded represent the preliminary fair values of and approximates the amounts a market participant would pay for these intangible assets as of the acquisition date.

The fair value of accounts receivables acquired is $5,873, with the gross contractual amount being $6,453. The Company expects $580 to be uncollectible.

Goodwill

The excess of the consideration for the acquisition over the preliminary fair value of net assets acquired was recorded as goodwill. The estimated goodwill recognized is attributable primarily to expected synergies and expanded market opportunities from combining the Company’s operations with those of Voxbone. The goodwill created in the acquisition is not expected to be deductible for tax purposes and is subject to revision as the purchase price allocation is completed. Goodwill arising from the acquisition has been allocated to the CPaaS reporting segment.

Transaction Costs

The Company recognized $14,458 of acquisition related costs that were expensed in the current period. These costs consist of mainly fees for financial and legal services, due diligence services, success fees, and net loss on foreign currency exchange directly associated with cash payments in foreign currencies as instructed by SPA of which $12,675 is included in general and administrative expenses and $1,783 is included in other income (expense), net in the consolidated statements of operations.

Results of Voxbone Subsequent to the Acquisition

The operating results of Voxbone have been included in the Company’s consolidated financial statements from the date of acquisition through December 31, 2020. The Company’s consolidated statement of operations for the year ended December 31, 2020 included revenues of $17,541 and a net loss of ($3,112), which includes the effects of purchase accounting adjustments, primarily the amortization of intangible assets.

Unaudited Pro Forma Information

The following unaudited pro forma financial information summarizes the combined results of operations for the Company and Voxbone as if the acquisition had been completed on January 1, 2019. The pro forma results have been prepared for comparative purposes only, and do not necessarily represent what the revenue or results of operations would have been had the acquisition been completed on January 1, 2019. In addition, these results are not intended to be a projection of future operating results and do not reflect synergies that might be achieved.

The unaudited pro forma information includes adjustments for the preliminary purchase price accounting impact (including, but not limited to, amortization for intangible assets, the purchase accounting effect on deferred revenue, transaction costs and related tax impacts) and the alignment of accounting policies. The pro forma results for the period ending December 31, 2020 also include the non-recurring transaction costs totaling $14,458.


	Year ended December 31,
	2019		2020
	(Unaudited)
Revenue	$	297,377	$	411,830
Net loss attributable to common stockholders	$	(7,737)	$	(42,675)

Fair Value Measurements

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurements

4. Fair Value Measurements

The carrying amounts of cash and cash equivalents, other investments, accounts receivable, accounts payable and accrued expenses approximate fair value as of December 31, 2019 and 2020 because of the relatively short duration of these instruments.

The Company evaluated its financial assets and liabilities subject to fair value measurements on a recurring basis to determine the appropriate level in which to classify them for each reporting period.

The following table summarizes the assets measured at fair value as of December 31, 2019 and December 31, 2020:


				Fair value measurements on a recurring basis December 31, 2019
	Level 1	Level 2	Level 3	Total
Financial assets:
Cash and cash equivalents:
Money market account				$	25,000	$	—	$	—	$	25,000
Time deposits				75,250		—		—		75,250










Total financial assets				$	100,250	$	—	$	—	$	100,250


				Fair value measurements on a recurring basis December 31, 2020
	Level 1	Level 2	Level 3			Total
Financial assets:
Cash and cash equivalents:
Money market account				$	57,517		$	—	$	—	$	57,517









Other investments:
Time deposits				40,000			—		—		40,000

Total financial assets				$	97,517		$	—	$	—	$	97,517

As of December 31, 2020, the fair value of the Convertible Notes, as further described in Note 9, “Debt”, was approximately $716,250. The fair value was determined based on the closing price for the Convertible Notes on the last trading day of the reporting period and is considered as Level 2 in the fair value hierarchy.

As of December 31, 2020, the fair value of the Pension Plan's assets, as further described in Note 14, “Employee Benefit Plan”, was approximately $2,882. The fair value was determined by an independent actuary and is considered as Level 2 in the fair value hierarchy.

The Company monitors the availability of observable market data to assess the appropriate classification of financial instruments within the fair value hierarchy. Changes in economic conditions or model-based valuation techniques may require the transfer of financial instruments from one fair value level to another. In such instances,

the transfer is reported at the beginning of the reporting period. There were no transfers between Levels 1, 2 or 3 during the years ended December 31, 2019 and 2020.

The money market account is included in cash and cash equivalents in the consolidated balance sheets as of December 31, 2019 and December 31, 2020.

During the December 31, 2018, 2019 and 2020 there were $18,000, $69,000 and $0 in maturities of marketable securities, respectively.

There were no sales of marketable securities for the years ended December 31, 2018 and 2020. Proceeds and gross realized gains from sales of marketable securities were $17,467 and $4, respectively for the year ended December 31, 2019. The cost of the securities sold was based on the specific identification method and the gross realized gain is recorded as other income, net, in the consolidated statements of operations.

Interest earned on marketable securities was $77, $6, and $0 for the years ended December 31, 2018, 2019 and 2020 respectively, and is recorded within other income (expense), net in the accompanying consolidated statements of operations.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Financial Statement Components

12 Months Ended

Dec. 31, 2020

Financial Statement Components [Abstract]

Financial Statement Components

5. Financial Statement Components

Accounts receivable, net of allowances consist of the following:


	As of December 31,
	2019		2020
Trade accounts receivable	$	14,692	$	26,504
Unbilled accounts receivable	16,200		27,692
Allowance for doubtful accounts and reserve for expected credit losses	(769)		(1,203)
Other accounts receivable	64		2,250
Total accounts receivable, net	$	30,187	$	55,243

Components of allowance for doubtful accounts and reserve for expected credit losses are as follows:


	Year ended December 31,
		2019		2020
Allowance for doubtful accounts:
Balance, beginning of period		$	(906)	$	(769)
Charged to bad debt expense		(1,543)		(1,322)
Deductions (1)		1,680		888



Balance, end of period		$	(769)	$	(1,203)

________________________

(1) Write off of uncollectible accounts after all collection efforts have been exhausted.

Accrued expenses and other current liabilities consisted of the following:


	As of December 31,
	2019		2020
Accrued expense	$	12,701	$	31,549
Accrued compensation and benefits	8,284		19,534
Accrued sales, use, VAT and telecommunications related taxes	5,439		9,142

Other accrued expenses	904		2,657
Current portion of finance lease	—		183
Total accrued expenses and other current liabilities	$	27,328	$	63,065

Right-of-Use Asset and Lease Liabilities

12 Months Ended

Dec. 31, 2020

Leases [Abstract]

Right-of-Use Asset and Lease Liabilities

6. Right-of-Use Asset and Lease Liabilities

In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). Under the new standard, lessees are required to recognize in the balance sheet the right-of-use (“ROU”) assets and lease liabilities that arise from operating leases. As a result of the Company no longer qualifying as an “emerging growth company” based on its public float as of the end of the three months ended June 30, 2019, the ASU was adopted as of December 31, 2019 with an effective date as of the beginning of the Company’s fiscal year, January 1, 2019. The standard was applied to the operating leases that existed on that date using the optional alternative method on a prospective basis. Prior year comparative financial information was recast under the new standard to be presented under ASC 842.

ROU assets represent the Company’s right to use an underlying asset for the lease term, and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. The Company determines if an arrangement is a lease at inception. ROU assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. Operating lease expense attributable to lease payments is recognized on a straight-line basis over the lease term and is included in cost of sales and selling, general, and administrative expense on our consolidated statement of operations. Finance leases result in the recognition of depreciation expense, which is recognized on a straight-line basis over the expected life of the leased asset, and interest expense, which is recognized following an effective interest rate method. Depreciation expense attributable to finance leases is included in cost of sales on our consolidated statement of operations. The Company presents the operating leases in long-term assets and current and long-term liabilities in the accompanying consolidated balance sheet as of December 31, 2020. Finance leases are reported in property and equipment, net, accrued expenses and other current liabilities, and other liabilities on the Company's consolidated balance sheet.

The Company sub-leases approximately 17,073 square feet of office space to a related party, Republic Wireless, Inc. (“Republic”). Future minimum sub-lease receipts required under the non-cancellable lease are as follows:


	As of December 31,
	2020

2021	$	457
2022	249


	$	706

As of December 31, 2020, the Company had various leased properties in the United States and the rest of the world, with remaining lease terms of eleven months to 6 years, some of which include options to extend the leases for up to 5 years. None of the options to extend the leases are recognized in operating lease ROU assets or lease

liabilities. The Company has one lease with an early-termination option, which it does not expect to exercise.

The components of lease expense recorded in the consolidated statement of operations were as follows:


	Year ended December 31,
		2019		2020
Operating lease cost		$	5,548	$	5,949
Finance lease cost:
Amortization of assets		—		20
Interest on lease liabilities		—		2


Sublease income (1)		(643)		(384)
Total net lease cost		$	4,905	$	5,587

________________________

(1) See Note 16, “Related Parties” to these consolidated financial statements, for additional details on sublease income.

During the years ended December 31, 2019 and 2020, short-term operating lease expense were $22 and $199, respectively.

Supplemental balance sheet information related to leases was as follows:


		As of December 31,
Leases	Classification	2019		2020
Assets:
Operating lease assets	Operating right-of-use asset, net (1)	$	21,031	$	19,491
Finance lease assets	Property and equipment, net (2)	—		464
Total leased assets		$	21,031	$	19,955

Liabilities:
Current
Operating	Operating lease liability, current	$	4,876	$	5,515
Finance	Accrued expenses and other current liabilities	—		183
Non-current
Operating	Operating lease liability, net of current portion	19,868		17,202
Finance	Other liabilities	—		282
Total lease liabilities		$	24,744	$	23,182

________________________

(1) Operating lease assets are recorded net of accumulated amortization of $4,269 and $9,083 as of December 31, 2019 and December 31, 2020, respectively.

(2) Finance lease assets are recorded net of accumulated depreciation of $0 and $28 as of December 31, 2019 and December 31, 2020, respectively.

Supplemental cash flow and other information related to leases was as follows:


	Year ended December 31,
		2019			2020
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases		$	3,357		$	5,301

Financing cash flows from finance leases		—			28
		$	3,357		$	5,329

Weighted average remaining lease term (in years)
Operating leases		4.35			3.79
Finance leases		—			2.99

Weighted average discount rate
Operating leases		4.98		%	4.81		%
Finance leases		—		%	4.00		%

Maturities of operating lease liabilities were as follows:


	As of December 31,
	2020

2021	$	6,408
2022	6,755
2023	6,623
2024	2,701
2025	1,681
Thereafter	751
Total lease payments	24,919
Less: imputed interest	(2,202)
Less: accrued lease incentive	—
Total lease obligations	22,717
Less: current obligations	(5,515)
Long-term lease obligations	$	17,202

Maturities of financing lease liabilities were as follows:


	As of December 31,
	2020

2021	$	195
2022	146
2023	92
2024	55
2025	4

Total lease payments	492
Less: imputed interest	(27)

Total lease obligations	465
Less: current obligations	(183)
Long-term lease obligations	$	282

Asset Retirement Obligation

The Company has an obligation to return one of its leased properties to its original leased condition. These cost are accrued at the present value of expected cost to settle the obligation using estimated cash flows. The cash flows are discounted at a current pre-tax rate that reflects the risk specific to the retirement liability. The estimated future cost of restoration is reviewed annually and adjusted as appropriate. As of December 31, 2020, asset retirement obligation was $240 included in other liabilities.

Property and Equipment

12 Months Ended

Dec. 31, 2020

Property, Plant and Equipment [Abstract]

Property and Equipment

7. Property and Equipment

Property and equipment, net consisted of the following:


	As of December 31,
	2019		2020
Furniture and fixtures	$	2,373	$	2,341
Computer and office equipment	4,627		4,077
Telecommunications equipment	44,324		60,651
Leasehold improvements	5,263		6,285
Software	2,018		3,901
Internal-use software development	17,952		19,968
Automobile	10		502
Total cost	76,567		97,725
Less—accumulated depreciation	(34,913)		(46,080)
Total property and equipment, net	$	41,654	$	51,645

The Company capitalizes the costs to design software for internal use related to the development of its platform during the application development stage of the projects. The costs are primarily comprised of salaries and benefits of the projects’ engineers and product development teams. Internally developed software is reported at cost less accumulated amortization. Amortization begins once the project is substantially complete and ready for its intended use. The Company amortizes the asset on a straight-line basis over the useful life, which is estimated to be 4 years. Costs incurred prior to the application development stage, maintenance activities or minor upgrades are expensed in the period incurred. Unamortized software development costs were approximately $5,746 and $5,957 as of December 31, 2019 and 2020, respectively.

The Company capitalized $2,028, $3,612 and $2,319 of software development costs for the years ended December 31, 2018, 2019 and 2020, respectively.

Amortization expense related to capitalized software development costs were $1,482, $2,024, and $1,963 for the years ended December 31, 2018, 2019 and 2020, respectively.

As of December 31, 2020, unamortized implementation costs related to cloud computing arrangements are $572, of which $144 are included in prepaid expenses and other current assets and $429 are included in other long-term assets.

The Company leases automobiles under leases accounted for as finance leases with expiration dates ranging from December 31, 2021 to April 30, 2025. As of December 31, 2020, cost and accumulated depreciation of the assets under finance leases recorded by the Company were $492 and $28, respectively. There were no finance leases as of December 31, 2019.

The Company recognized an impairment of $158, $275, and $227 during the years ended December 31, 2018, 2019 and 2020, respectively, related to capitalized software development costs that provided no future benefit and therefore were impaired. This expense is reflected within cost of revenue in the accompanying consolidated statements of operations.

The Company recognized depreciation expense, which includes amortization of capitalized software development costs, as follows:


	Year ended December 31,
		2018		2019		2020
Cost of revenue		$	4,490	$	6,583	$	9,536
Research and development		161		268		670
Sales and marketing		51		112		120
General and administrative		568		2,055		2,811
Total depreciation expense		$	5,270	$	9,018	$	13,137

Goodwill and Intangible Assets

12 Months Ended

Dec. 31, 2020

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and Intangible Assets

8. Goodwill and Intangible Assets

Goodwill

The changes in carrying amount of goodwill were as follows:


	Total
Balance as of December 31, 2019	$	6,867
Goodwill additions related to 2020 acquisition	346,564
Impact of foreign currency translation	18,808
Balance as of December 31, 2020	$	372,239

Intangible Assets

Intangible assets, net consisted of the following as of December 31, 2019:


	Gross Amount		Accumulated Amortization		Net Carrying Value		Amortization Period
Dash acquisition and other intangibles:							(Years)
Customer relationships	$	10,396	$	(4,591)	$	5,805	20




Other, definite lived	3,933		(3,933)		—		2 - 7
Licenses, indefinite lived	764		—		764		Indefinite
Total intangible assets, net	$	15,093	$	(8,524)	$	6,569

Intangible assets, net consisted of the following as of December 31, 2020:


	Gross Amount		Accumulated Amortization		Net Carrying Value		Amortization Period
Dash acquisition and other intangibles:							(Years)
Customer relationships	$	10,396	$	(5,111)	$	5,285	20




Other, definite lived	3,933		(3,933)		—		2 - 7
Licenses, indefinite lived	764		—		764		Indefinite
Total Dash acquistion and other intangible assets	15,093		(9,044)		6,049

Voxbone acquistion:
Customer relationships	156,559		(1,739)		154,820		15
Developed technology	88,664		(1,478)		87,186		10
Total Voxbone acquisition	245,223		(3,217)		242,006

Total intangibles, net	$	260,316	$	(12,261)	$	248,055

Amortization expense for definite lived intangible assets was $554, $520, $3,666 for the years ended December 31, 2018, 2019 and 2020 respectively. The remaining weighted average amortization period for definite lived intangible assets is 13 years.

Future estimated amortization expense for definite lived intangible assets is as follows:


	As of December 31,
	2020

2021	$	19,824
2022	19,824
2023	19,824
2024	19,824
2025	19,824

Thereafter	148,171
	$	247,291

Debt

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

Debt

9. Debt

Revolving Loan

On March 1, 2019, the Company amended and restated its Credit and Security Agreement with KeyBank National Association (“KeyBank”). The agreement is for a $25,000 revolving loan, which includes a swing line of up to $1,000 and limits letters of credit commitments to a maximum of $2,500. The term of the amended and restated Credit and Security Agreement is 3 years and matures on March 1, 2022. Loans under the Credit Agreement will bear interest at the highest of (i) the bank’s prime rate, (ii) the federal funds effective rate plus 0.5 percent, and (iii) the London Interbank Offered Rate plus 1.00 percent. This agreement requires that a specified minimum liquidity amount must be maintained in cash and cash equivalents at all times and that the Company meet a minimum revenue clause on a quarterly basis.

On June 4, 2019, KeyBank and Pacific Western Bank entered into an Assignment and Acceptance Agreement, whereby KeyBank, as the Assignor, sold and assigned $10,000 of the Company's Revolving Credit Commitment to Pacific Western Bank, the Assignee. KeyBank retains $15,000 of the Revolving Credit Commitment.

On February 25, 2020, the Company entered into a waiver agreement with respect to its revolving loan (the “Credit Facility”) with KeyBank National Association and Pacific Western Bank (the “Lenders”), which provided for consent to accommodate the issuance of the Convertible Notes and entry into the Capped Calls (as defined below). The waiver agreement (“Cash Collateral Requirement”) required the Company to covenant with the Lenders to deposit an amount of funds into a controlled account, which restricted the ability to use such funds until the Credit Facility was paid in full or terminated. If the Company had failed to comply with these covenants or to make payments under its indebtedness when due, the Company would have been in default under that indebtedness, which could, in turn, have resulted in that indebtedness becoming immediately payable in full. On April 27, 2020, the First Amendment Agreement to the Credit Security Agreement was executed in which the Lenders consented to remove the cash collateral requirement and to terminate the controlled account.

As of December 31, 2019, unamortized debt issuance costs were $125, of which $70 were in included in prepaid expenses and other current assets and $55 were included in other long-term assets. As of December 31, 2020, the outstanding debt issuance costs are $83, of which $74 are included in prepaid expenses and other current assets and $9 are included in other long-term assets.

As of December 31, 2019 and December 31, 2020, the Company had $0 outstanding on the Credit Facility and was in compliance with all financial and non-financial covenants for all periods presented. The available borrowing capacity under the Credit Facility was $25,000 as of December 31, 2020.

Convertible Senior Notes and Capped Call Transactions

On February 28, 2020, the Company issued $400,000 aggregate principal amount of 0.25% Convertible Notes due March 1, 2026 in a private placement to qualified institutional buyers pursuant to Rule 144A under the Securities Act (the “Convertible Notes”). The interest on the Convertible Notes is payable semi-annually in arrears on March 1 and September 1 of each year, beginning on September 1, 2020.

The Convertible Notes may bear special interest under specified circumstances relating to the Company's failure to comply with its reporting obligations under the indenture governing the Convertible Notes (the “Indenture”) or if the Convertible Notes are not freely tradeable as required by the Indenture. The Convertible Notes will mature on March 1, 2026, unless earlier repurchased, redeemed by the Company, or converted pursuant to their terms. The total net proceeds from the Convertible Notes, after deducting initial purchaser discounts, costs related to the Capped Calls, and debt issuance costs, paid by the Company, were approximately $344,722.

Each $1 principal amount of the Convertible Notes is initially convertible into 10.9857 shares of the Company's Class A common stock, par value $0.001 per share, which is equivalent to an initial conversion price of approximately $91.03 per share. The conversion rate is subject to adjustment upon the occurrence of certain specified events but will not be adjusted for any accrued and unpaid special interest. In addition, upon the occurrence of a make-whole fundamental change, as defined in the indenture, the Company will, in certain circumstances, increase the conversion rate by a number of additional shares for a holder that elects to convert its Convertible Notes in connection with such make-whole fundamental change or during the relevant redemption period.

The Convertible Notes will be redeemable in whole or in part at the Company's option on or after March 6, 2023, but before the 40th scheduled trading day before the maturity date, at a cash redemption price equal to 100% of the principal amount of the Convertible Notes to be redeemed, plus accrued and unpaid interest, if any, if the last reported sale price of the Class A common stock has been at least 130% of the conversion price then in effect for at least 20 trading days (whether or not consecutive) during any 30 consecutive trading days ending on, and including, the trading day immediately before the date the redemption notices were sent; and the trading day immediately before such notices were sent.

Prior to the close of business on the business day immediately preceding September 1, 2025, the Convertible Notes may be convertible at the option of the holders only under the following circumstances:

(1)during any calendar quarter commencing after the calendar quarter ending on June 30, 2020 (and only during such calendar quarter), if the last reported sale price per share of the Company's Class A common stock exceeds 130% of the conversion price for each of at least 20 trading days, whether or not consecutive, during the 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter;

(2)during the five consecutive business days immediately after any 10 consecutive trading day period (such 10 consecutive trading day period, the “measurement period”) in which the trading price per $1 principal amount of Convertible Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price per share of the Company's Class A common stock on such trading day and the conversion rate on such trading day;

(3)upon the occurrence of certain corporate events or distributions on its Class A common stock; and

(4)if the Company calls such Convertible Notes for redemption.

On or after September 1, 2025, until the close of business on the second scheduled trading day immediately preceding the maturity date, holders of the Convertible Notes may, at their option, convert all or a portion of their Convertible Notes regardless of the foregoing conditions.

During the year ended December 31, 2020, the conditional conversion feature of the Notes was triggered as the last reported sale price of the Company's Class A common stock was more than or equal to 130% of the conversion price for at least 20 trading days (whether or not consecutive) in the period of 30 consecutive trading days ending on or after June 30, 2020 (the last trading day of the calendar quarter), and therefore the Notes were convertible, in whole or in part, at the option of the holders between July 1, 2020 through December 31, 2020. Whether the Notes will be convertible following such period will depend on the continued satisfaction of this condition or another conversion condition in the future. The Company continues to classify the Notes as a long-term liability in its consolidated balance sheet as of December 31, 2020, based on contractual settlement provisions.

Upon conversion, the Company will pay or deliver, as the case may be, cash, shares of Class A common stock, or a combination of cash and shares of Class A common stock, at the Company's election. It is the Company's current intent to settle the principal amount of the Convertible Notes with cash.

No sinking fund is provided for the Convertible Notes. Upon the occurrence of a fundamental change (as defined in the indenture) prior to the maturity date, holders may require the Company to repurchase all or a portion of the Convertible Notes for cash at a price equal to the principal amount of the Convertible Notes to be repurchased, plus any accrued and unpaid interest to, but excluding, the fundamental change repurchase date.

The Convertible Notes are the senior, unsecured obligations of the Company and are equal in right of payment with the Company’s existing and future senior unsecured indebtedness, senior in right of payment to the Company’s existing and future indebtedness that is expressly subordinated to the Convertible Notes and effectively subordinated to the Company’s existing and future senior secured indebtedness (including the Company’s $25,000 Credit Facility), to the extent of the value of the collateral securing that indebtedness. The Convertible Notes will be structurally subordinated to all existing and future indebtedness and other liabilities, including trade payables, and preferred equity, if any, of the Company’s subsidiaries.

In accounting for the issuance of the Convertible Notes, the Company separated the Convertible Notes into liability and equity components. The carrying amount of the liability component was calculated by measuring the fair value of a similar debt instrument that does not have an associated convertible feature. The carrying amount of the equity component representing the conversion option was $125,152 and was determined by deducting the fair value of the liability component from the par value of the Convertible Notes. The difference represents the debt discount that is amortized to interest expense at an effective interest rate of 6.763% over the term of the Convertible Notes. The carrying amount of the equity component was $57,485 and is recorded in additional paid-in-capital. The equity component is not remeasured as long as it continues to meet the conditions for equity classification. The excess of the principal amount of the liability component over its carrying amount, or the debt discount, is amortized to interest expense at an annual effective interest rate of 6.907% over the contractual terms of the Convertible Notes.

In accounting for the transaction costs related to the Convertible Notes, the Company allocated the total amount incurred to the liability and equity components of the Convertible Notes based on the proportion of the proceeds allocated to the debt and equity components. Issuance costs attributable to the liability component were approximately $8,217, were recorded as an additional debt discount and are amortized to interest expense using the effective interest method over the contractual terms of the Convertible Notes. Issuance costs attributable to the equity component of $3,742 were netted with the equity component in stockholders’ equity.

The net carrying amount of the liability component of the Convertible Notes was as follows:


	As of December 31,
	2020
Principal	$	400,000
Unamortized discount	(110,546)
Unamortized debt issuance costs	(7,258)
Net carrying amount	$	282,196

The net carrying amount of the equity component of the Convertible Notes was as follows:


	As of December 31,
	2020
Proceeds allocated to the conversion options (debt discount)	$	125,152
Issuance costs	(3,742)
Net carrying amount	$	121,410

The following table sets forth the interest expense recognized related to the Convertible Notes:


	Year ended December 31,
		2020
Contractual interest expense		$	841
Amortization of debt discount		14,606
Amortization of debt issuance costs		959
Total interest expense related to the Convertible Notes		$	16,406

In connection with the offering of the Convertible Notes, the Company entered into privately negotiated capped call transactions with certain counterparties (the “Capped Calls”). The Capped Calls each have an initial strike price of approximately $91.03 per share, subject to certain adjustments, which corresponds to the initial conversion price of the Convertible Notes. The Capped Calls have initial cap prices of $137.40 per share, subject to certain adjustments. The Capped Calls cover, subject to anti-dilution adjustments, approximately 4,394,276 shares of Class A common stock. The Capped Calls are generally intended to reduce or offset the potential dilution to the Class A common stock upon any conversion of the Convertible Notes with such reduction or offset, as the case may be, subject to a cap based on the cap price. The Capped Calls expire on the earlier of (i) the last day on which any convertible securities remain outstanding and (ii) March 1, 2026, subject to earlier exercise. The Capped Calls are subject to either adjustment or termination upon the occurrence of specified extraordinary events affecting the Company, including a merger event, a tender offer, and a nationalization, insolvency or delisting involving the Company. In addition, the Capped Calls are subject to certain specified additional disruption events that may give rise to a termination of the Capped Calls, including changes in law, insolvency filings, and hedging disruptions. The Capped Call transactions are recorded in stockholders’ equity and are not accounted for as derivatives. The net cost of $43,320 incurred to purchase the Capped Calls was recorded as a reduction to additional paid-in capital in the accompanying consolidated balance sheets.

Segment and Geographic Information

12 Months Ended

Dec. 31, 2020

Segment Reporting [Abstract]

Segment and Geographic Information

10. Segment and Geographic Information

The Company has two reportable segments, CPaaS and Other. Segments are primarily evaluated based on revenue and gross profit. The Company does not allocate operating expenses, interest expense or income tax expense to its segments. Accordingly, the Company does not report such information. Additionally, the Chief Operating Decision Maker does not evaluate the Company’s operating segments using discrete asset information. The segments share the majority of the Company’s assets. Therefore, no segment asset information is reported.


	Year ended December 31,
		2018		2019		2020
CPaaS
Revenue		$	164,415	$	197,944	$	298,090
Cost of revenue		94,296		110,343		160,706
Gross profit		$	70,119	$	87,601	$	137,384
Other
Revenue		$	39,698	$	34,650	$	45,023
Cost of revenue		13,849		14,616		24,546
Gross profit		$	25,849	$	20,034	$	20,477
Consolidated
Revenue		$	204,113	$	232,594	$	343,113
Cost of revenue		108,145		124,959		185,252
Gross profit		$	95,968	$	107,635	$	157,861

The Company's long-lived assets were primarily held in the United States as of December 31, 2019 and December 31, 2020. As of December 31, 2019 and December 31, 2020, long-lived assets held outside of the United States were $2,924 and $11,249, respectively.

The Company generates its revenue primarily in the United States. Revenue by geographic area is detailed in the table below (which is determined based on the customer billing address):


	Year ended December 31,
		2018		2019		2020
CPaaS
United States		$	164,135	$	192,506	$	281,757
International		280		5,438		16,333
Total		$	164,415	$	197,944	$	298,090

Other
United States		$	39,432	$	33,664	$	42,692
International		266		986		2,331
Total		$	39,698	$	34,650	$	45,023

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Stockholders' Equity

12 Months Ended

Dec. 31, 2020

Equity [Abstract]

Stockholders' Equity

11. Stockholders’ Equity

Preferred Stock

As of December 31, 2019 and December 31, 2020, the Company had authorized 10,000,000 shares of undesignated preferred stock, par value $0.001, of which no shares were issued and outstanding.

Common Stock

As of December 31, 2019 and December 31, 2020, the Company had authorized 100,000,000 shares of Class A common stock, par value $0.001 per share, with one vote per share and 20,000,000 shares of Class B common stock, par value $0.001 per share, with ten votes per share. As of December 31, 2019, 18,584,478 and 4,927,401 shares of Class A common stock and Class B common stock, respectively, were issued and outstanding.

As of December 31, 2020, 22,413,004 and 2,496,125 shares of Class A common stock and Class B common stock, respectively, were issued and outstanding.

Shares of Class B common stock are convertible into shares of Class A common stock upon the stockholder’s voluntary written notice to the Company’s transfer agent or a transfer by the stockholder, subject to limited exceptions for transfers for estate planning purposes.

Voting Rights

The holders of Class A common stock and Class B common stock have identical rights, except that holders of Class A voting common stock are entitled to one vote per share of Class A common stock and holder of Class B common stock are entitled to ten votes per share of Class B common stock.

Dividends

Any dividends or distributions paid or payable to the holders of shares of Class A common stock and Class B common stock shall be paid pro-rata, on an equal priority. During the years ended December 31, 2018, 2019 and 2020, no dividends were declared.

Dividend payments are subject to a restriction by the Company’s Credit and Security Agreement prohibiting the Company to pay any dividends or any other distribution or payment on account of or in redemption, retirement or purchase of any capital stock through the term of the agreement.

Reserved Shares

The Company had reserved shares of Class A common stock for issuance under stock-based award agreements as follows:


	As of December 31,
	2019	2020
Stock options issued and outstanding	853,399	255,000
Nonvested restricted stock units issued and outstanding	392,351	450,614
Stock-based awards available for grant under the 2017 Plan	1,310,354	2,020,342
	2,556,104	2,725,956

Stock Based Compensation

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

Stock Based Compensation

12. Stock Based Compensation

2010 Stock Option Plan

As of July 26, 2010, the Company adopted the 2010 Equity Compensation Plan (the “2010 Plan”).

Eligible plan participants include employees, directors and consultants. The 2010 Plan permits the granting of incentive stock options and non-qualified stock options.

On November 9, 2017, the 2010 Plan was terminated in connection with the Company’s initial public offering. Accordingly, no shares are available for future issuance under the 2010 Plan. However, the 2010 Plan continues to govern the terms and conditions of the outstanding awards granted thereunder.

2017 Incentive Award Plan

The Company’s 2017 Incentive Award Plan (the “2017 Plan”) became effective on November 9, 2017. The 2017 Plan provides for the grant of stock options, including incentive stock options and non-qualified stock options, stock appreciation rights, restricted stock, dividend equivalents, restricted stock units, and other stock or cash based awards to employees, consultants and directors of the Company. A total of 1,050,000 shares of the Company’s

Class A common stock were originally reserved for issuance under the 2017 Plan. These available shares automatically increase each January 1, beginning on January 1, 2018, by 5% of the number of shares of the Company’s Class A common stock outstanding on the final day of the immediately preceding calendar year. On January 1, 2020, the shares available for grant under the 2017 Plan were automatically increased by 929,224 shares for a total of 2,239,578.

The terms of the stock option grants are determined by the Company’s Board of Directors. The Company’s stock options vest based on terms of the stock option agreements, which is generally over four years. The stock options have a contractual life of ten years.

Restricted stock units (“RSUs”) granted under the 2017 Plan are subject to a time-based vesting condition. The compensation expense related to these awards is based on the grant date fair value of the RSUs and is recognized on a ratable basis over the applicable service period. The Company granted RSUs to its non-employee Board of Directors, some of which vested immediately while others vest 25% as of each calendar quarter immediately following the grant date. Certain RSUs awarded to executives vest over four years with 50% vesting in the first year in 12.5% increments on each calendar quarter immediately following the grant date and the remaining 50% earned over years two, three and four. Other RSUs awarded to executives and employees generally are earned over a service period of four years.

Stock Options

The following summarizes the stock option activity for the periods presented:


	Number of options outstanding	Weighted- average exercise price (per share)		Weighted- average remaining contract life (in years)	Aggregate intrinsic value (in thousands)
Outstanding as of December 31, 2019	853,399	$	8.07	3.41	$	47,770
Granted	—	—
Exercised	(593,084)	6.87			54,088
Forfeited or cancelled	(5,315)	10.30
Outstanding as of December 31, 2020	255,000	$	10.82	4.42	$	36,426

Options vested and exercisable at December 31, 2020	223,883	$	9.99	4.11	$	32,168
Options vested and expected to vest as of December 31, 2020	254,826	$	10.82	4.41	$	36,403

Aggregate intrinsic value is computed based on the difference between the option exercise price and the fair value of the Company’s common stock as of December 31, 2020, based on the Company’s Class A common stock price as reported on the NASDAQ Global Select Market.

No options were granted for the year ended December 31, 2020.

The total estimated grant date fair value of options vested was $979, $729, and $416 for the years ended December 31, 2018, 2019 and 2020, respectively.

As of December 31, 2020, total unrecognized compensation cost related to all non-vested stock options was $152, which will be amortized over a weighted-average period of 0.66 years.

Restricted Stock Units

The following summarizes the RSU activity for the periods presented:


	Number of awards outstanding	Weighted-average grant date fair value (per share)
Nonvested RSUs as of December 31, 2019	392,351	$	35.22
Granted	234,653	73.86
Vested	(161,067)	44.42
Forfeited or cancelled	(15,323)	49.21
Nonvested RSUs as of December 31, 2020	450,614	$	51.58

As of December 31, 2020, total unrecognized compensation cost related to non-vested RSUs was $18,319, which will be amortized over a weighted-average period of 2.72 years.

Stock-Based Compensation Expense

The Company recognized total stock-based compensation expense as follows:


	Year ended December 31,
		2018		2019		2020
Cost of revenue		$	114	$	211	$	208
Research and development		555		1,461		2,118
Sales and marketing		511		1,199		1,525
General and administrative (1)		2,159		3,755		6,030
Total		$	3,339	$	6,626	$	9,881

________________________

(1) On December 21, 2018, the Company reached a separation agreement with an executive. The agreement resulted in a modification of the former employee’s 17,725 non-vested restricted stock units, which accelerated the vesting period, resulting in the recognition of $535 of additional stock compensation expense for the year ended December 31, 2018.

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	13. Commitments and Contingencies Operating Leases The Company leases office space under operating lease agreements that expire over the next 6.00 years. See Note 6, “Right-of-Use Asset and Lease Liabilities” to the consolidated financial statements, for additional details on the Company's operating lease commitments. Contractual Obligations On October 25, 2015, the Company entered into an agreement with a telecommunications service provider. The service agreement requires the Company to pay a monthly recurring charge beginning on January 1, 2016 associated with the services received. The service agreement is non-cancellable and contains annual minimum commitments of $1,200, to be fulfilled over five years or for as long as the Company continues to receive services from this vendor. On August 1, 2020, the Company amended the agreement to require annual minimum commitments of $600 and $300 in 2021 and 2022, respectively. In addition, as of December 31, 2020, the Company has $13,378 in other non-cancellable purchase obligations, consisting of primarily network equipment maintenance and software license contracts, of which $8,428 will be fulfilled within one year. On May 16, 2020, the Company entered into an indemnity agreement with a development company (the “developer”) relating to predevelopment work for approximately 40 acres of vacant land in Raleigh, North Carolina, currently owned by the State of North Carolina (the “State”), upon which the Company intends to construct its office headquarters. The indemnity agreement requires the Company to reimburse the developer one-half of the predevelopment work expenses plus two-thirds of a near future amount to be incurred, to a maximum of $597, if certain conditions are not satisfied. As of December 31, 2020, the Company expects all of the required conditions to be satisfied. On June 15, 2020, the Company signed a Purchase and Sale Agreement (the “Purchase and Sale Agreement”) with the State regarding the proposed sale to Bandwidth of the approximately 40 acres of vacant land located at the southwest quadrant of Reedy Creek Road and Edwards Mill Road in Raleigh, North Carolina (the “Land”). The consideration for the proposed sale of the Land to Bandwidth is $30,000. As part of the purchase and Sale Agreement, the Company is obligated to provide and improve parking facilities for the use by the State of NC which were previously located on the Land. The Purchase and Sale Agreement is subject to due diligence, approvals and other customary closing conditions. Legal Matters The Company is involved as a defendant in various lawsuits alleging that the Company failed to bill, collect and remit certain taxes and surcharges associated with the provision of 911 services pursuant to applicable laws in various jurisdictions. While the results of these legal proceedings cannot be predicted with certainty, in the opinion of management, the ultimate resolution of these matters will not have a material adverse effect on the Company’s financial position or results of operations.

Employee Benefit Plan

12 Months Ended

Dec. 31, 2020

Retirement Benefits [Abstract]

Employee Benefit Plan

14. Employee Benefit Plan

The Company sponsors a U.S. defined contribution 401(k), which allows eligible U.S.-based employees to defer a portion of their compensation. The Company, at its discretion, may make matching contributions. With the acquisition of Voxbone S.A. on November 1, 2020, the Company assumed sponsorship for their U.S. defined contribution 401(k). The Company also assumed sponsorship for a non-U.S. defined contribution plan for which they pay fixed contributions into a separate entity. The Company has no legal or constructive obligations to pay further contributions if the fund does not hold sufficient assets to pay all employees the benefits relating to employee service in the current or prior periods. The contributions are recognized as employee benefit expense when they are due. The Company made matching contributions for the defined contribution plans of $1,117, $1,731, and $2,202 for the years ended December 31, 2018, 2019 and 2020, respectively.

In addition, as a result of the acquisition of Voxbone S.A., the Company assumed sponsorship for their non-U.S. defined benefit pension plans. The liability recognized in the balance sheet in respect to these plans is the present value of the defined benefit obligation at the end of the reporting period less the fair value of the plan assets. The defined benefit obligation is calculated annually by an independent actuary using the Projected Unit Credit Method.

The following table summarizes information for the pension plans:


	As of December 31,
	2020
Change in benefit obligation:
Benefit obligation at beginning of year	$	—
Service cost	75
Interest cost	3
Actuarial loss	15
Taxes, insurance premiums and administrative expenses	(9)
Acquisitions/plan mergers	3,980
Benefit obligation at end of year	$	4,064

Change in plan assets:
Fair value of plan assets at beginning of year	$	—
Return on plan assets	8
Actuarial loss	2
Employer contribution	57
Acquisitions/plan mergers	2,824
Taxes, insurance premiums and administrative expenses	(9)
Fair value of plan assets at end of year	2,882
Funded status, net liability	$	1,182

The following table presents the balance sheet location of the Company’s pension liability:


	As of December 31,
	2020
Other liabilities	$	1,182

The accumulated benefit obligation for the Company's non-U.S. defined benefit pension plans was $3,450 as of December 31, 2020.

The following table summarizes information for the Company's pension plans with an accumulated benefit obligation in excess of plan assets:


	As of December 31,
	2020
Projected benefit obligation	$	4,064
Accumulated benefit obligation	3,450
Fair value of plan assets	2,882

The Company reports the service cost component of net periodic benefit cost in the same line item as other compensation costs arising from the services rendered by the employee and records the other components of net periodic benefit cost in other expense, net.

Pretax amounts for net periodic benefit cost and other amounts included in other comprehensive income (loss) for the defined benefit pension plans consisted of the following components:


	Year ended December 31,
	2020
Service cost	$	75
Interest cost	3
Return on plan assets	(8)
Net periodic pension cost	70

Changes in plan assets and benefit obligations included in other comprehensive income (loss):
Change in net actuarial loss	17
Total (before tax effect)	17
Total recognized in net periodic benefit cost and included in other comprehensive income (loss)	$	87

The Company uses significant judgement to determine the measurement of their non-U.S. defined benefit pension plans’ assets and liabilities. These amounts are calculated by an independent actuary. The present value of the defined benefit obligation depends on a number of factors that are determined on an actuarial basis using a number of assumptions. Any change in these assumptions will impact the present value of the defined benefit obligation.

The Company determines the appropriate discount rate at the end of each year. This is the interest rate that should be used to determine the present value of estimated future cash outflows expected to be required to settle the pension obligations. In determining the appropriate discount rate, the Company considers the interest rates of high-quality corporate bonds that are denominated in the currency in which the benefits will be paid, and that have terms to maturity approximating the terms of the related obligation. The other assumptions for pension obligations are based in part on market conditions.

Significant assumptions used in determining benefit obligations and net periodic benefit cost are as follows:


	Year ended December 31,
	2020
Defined benefit obligations:
Discount rate	0.50	%
Rate of salary increase	4.07	%
Inflation	1.60	%

Defined benefit cost:
Discount rate	1.50	%
Rate of salary increase	4.37	%
Rate of return on plan assets	0.50	%
Inflation	1.90	%

Plan Assets

The Company’s non-U.S. defined benefit plans are insured by a third party. The investments are governed by the insurer, who oversees all investment decisions. The insurance contracts are classified as Level 2 because a portion of the underlying funds are valued using significant other observable inputs. The insurance contracts provide for a guaranteed interest credit and a profit-sharing adjustment based on the actual performance of the underlying investment assets of the insurer. The fair value of the contract is determined by the insurer based on the premiums paid by the Company plus interest credits plus the profit-sharing adjustment less benefit payments.

The major categories of plan assets are as follows:


	As of December 31,
	2020
Assets held by:
Insurance companies (collective)	$	2,853
Insurance companies (individual)	29
Total	$	2,882

Expected Cash Flows

The Company expects to contribute $341 to its non-U.S. defined benefit pension plans during 2021.

The following table summarizes projected benefit payments from the Company's pension plans through 2030, including benefits attributable to estimated future service:


	As of December 31,
	2020
2021	$	5
2022	5
2023	5
2024	35
2025	5
2026-2030	37
	$	92

- Definition

The entire disclosure for retirement benefits.

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-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

+ Details

Income Taxes

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Income Taxes

15. Income Taxes

The following table presents domestic and foreign components of income (loss) before income taxes for the tax years ended December 31, 2018, 2019 and 2020:


	Year Ended December 31,
	2018		2019		2020
United States	$	7,053	$	(15,229)	$	(25,745)
International	—		5		(3,227)
Income (loss) before income taxes	$	7,053	$	(15,224)	$	(28,972)

Benefit (provision) for income taxes from operations consists of the following:


	Year Ended December 31,

	2018		2019		2020
Current:
Federal	$	162	$	81	$	431
State	(125)		132		(87)
Foreign	—		3		(1,083)
Total	37		216		(739)
Deferred:
Federal	8,945		15,205		(9,847)
State	1,888		2,297		(5,176)
Foreign	—		—		757
Total	10,833		17,502		(14,266)
Income tax benefit (provision)	$	10,870	$	17,718	$	(15,005)

The following table presents a reconciliation of the statutory federal tax rate and the Company's effective tax rate for the years ended December 31, 2018, 2019 and 2020:


	Year Ended December 31,
	2018		2019		2020
Federal Tax Rate	21.0	%	21.0	%	21.0	%
State Tax Rate	6.3		3.1		2.0
Non-deductible expenses	1.7		(1.6)		(9.2)
Research credit	(13.6)		7.2		10.5
Stock-based compensation	(168.0)		88.6		46.8
Change in valuation allowance	—		—		(123.4)
Deferred tax rate change	(0.7)		(0.3)		0.2
Other	(0.8)		(1.6)		0.3
Total	(154.1)	%	116.4	%	(51.8)	%

The following table presents the significant components of the Company’s net deferred tax assets:


	As of December 31,
	2019		2020
Deferred tax assets:
Allowance for doubtful accounts	$	97	$	134
Accrued liabilities	2,083		3,478
Operating lease liabilities	6,335		4,878
Deferred revenue	1,682		1,702

Stock-based compensation - deferred tax asset	2,109		1,968
OID	—		9,433
Tax credits	3,710		7,270
Net operating losses	30,835		47,385
Other deferred tax assets	90		2,207
Total deferred tax assets	46,941		78,455
Less: valuation allowance	—		(37,771)
Net deferred tax assets	46,941		40,684
Deferred tax liabilities:
Property and equipment	5,793		8,038
Goodwill	855		989
Intangibles	41		60,667
Operating lease assets	5,295		4,092
Debt	—		27,766
Other liability	96		137
Total deferred tax liabilities	12,080		101,689
Net deferred tax asset (liability)	$	34,861	$	(61,005)

The Company’s accounting for deferred taxes involves the evaluation of a number of factors concerning the realizability of its net deferred tax assets. The Company primarily considered the historic performance of Bandwidth, the nature of the Company’s deferred tax assets and the timing, likelihood and amount, if any, of future taxable income during the periods in which those temporary differences and carryforwards become deductible. Based on an analysis of these factors, the Company determined that in 2020 a valuation allowance against US and UK deferred tax assets was required.

As of December 31, 2020, the Company had approximately $187,385 in US federal net operating loss carryforwards, $5,263 in UK loss carryforwards, and $9,653 in federal tax credits. All US federal net operating loss carryforwards were generated after the enactment of the Tax Cuts and Jobs Act (the “Act”) and as such do not expire, but can only be utilized to offset up to 80% of taxable income in any given year. The federal tax credits start to expire at various dates beginning in 2032.

As of December 31, 2020, the Company had approximately $125,334 in state net operating loss carryforwards. If not utilized, some state net operating loss carryforwards will expire at various dates beginning in 2023.

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:


	Year Ended December 31,
	2019		2020
Unrecognized tax benefits—January 1,	$	1,046	$	1,398
Gross increases—tax positions in prior period	—		402
Gross decreases—tax positions in prior period	(15)		—
Gross increases—tax positions in current period	367		614


Unrecognized tax benefits—December 31,	$	1,398	$	2,414

If the $2,414 of unrecognized tax benefit is recognized, it would not impact the effective tax rate.

The Company has not incurred any material tax interest or penalties with respect to income taxes in the years ended December 31, 2019 and 2020.

The Company expects no material changes in the twelve months following December 31, 2020 in its uncertain tax positions.

The Company files U.S. federal income tax returns as well as income tax returns in many U.S. states and foreign jurisdictions. The tax years 2017 - 2019 remain open to examination by the major jurisdictions in which the Company is subject to tax.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References + Details

Related Parties	12 Months Ended
Related Parties	Dec. 31, 2020
Related Party Transactions [Abstract]
Related Parties	16. Related Parties On April 20, 2015, the Company created a wholly owned subsidiary, Republic, which was incorporated in Delaware. On November 30, 2016, the Company completed a pro-rata distribution of the common stock of Republic to its stockholders of record as of the close of business (the “Spin-Off”). In connection with the Spin-Off on November 30, 2016, the Company and Republic entered into certain agreements in order to govern the ongoing relationships between the two companies after the Spin-Off and to provide for an orderly transition. The agreements include a Transition Services Agreement, Facilities Sharing Agreement, Tax Sharing Agreement, and Master Services Agreement. The equity holders of Bandwidth pre-initial public offering are comprised of substantially the same individuals and entities that are the equity owners of Republic. The Company has determined the equity owners of Republic are related parties of Bandwidth. The Company has certain involvement with Republic via ongoing services arrangements, with these ongoing services arrangements creating a variable interest in Republic. The Company assessed the relationship with Republic under guidance for variable interest entities (“VIE”). Because investors in Republic have disproportionate voting rights, the Company concluded that Republic is a VIE, but Bandwidth is not a primary beneficiary. The Company’s maximum exposure to loss relating to this VIE is limited to amounts due under the service agreements between the Company and Republic. The Company recorded a reduction of rent expense under the Facilities Sharing Agreement of $1,005, $643, and $384 for the years ended December 31, 2018, 2019 and 2020 respectively, which is included in general and administrative expenses in the consolidated statements of operations. No amounts were due to the Company under the Facilities Sharing Agreement as of December 31, 2019 and December 31, 2020. The Tax Sharing Agreement governs rights and obligations after the Spin-Off regarding income taxes and other taxes, including tax liabilities and benefits, attributes, returns and contests. There were no amounts outstanding or payable under this agreement as of December 31, 2019 and December 31, 2020. The Master Services Agreement specifies certain wholesale telecommunications services to be provided by the Company. The agreement is cancellable at any time by either party. The Company provided telecommunication services to Republic of $3,884, $2,602, and $2,180 for the years ended December 31, 2018, 2019 and 2020 respectively. The Company recognized such amounts as revenue in the accompanying consolidated statements of operations. As of December 31, 2019 and December 31, 2020, the Company had a receivable of $161 and $170, respectively, under the Master Services Agreement. On March 1, 2019, an amendment to the current Master Services Agreement was executed. Pursuant to the terms of the new agreement, Republic receives reduced pricing on its messaging services, effective April 1, 2019. All other terms and conditions of the existing agreement remain. On June 20, 2019, Republic executed a further amendment to the current Master Services Agreement. Pursuant to the terms of the June 20, 2019 amendment, Republic receives reduced pricing on its outbound voice services effective on June 20, 2019. Republic also executed a revenue commitment schedule on June 20, 2019. Pursuant to the revenue commitment schedule, Republic agreed to spend a minimum of $100 per month during the 11-month period commencing July 1, 2019 through May 31, 2020. There are no minimum commitments beyond May 31, 2020. Subsequent to the expiration of the 180-day IPO blackout window on May 9, 2018, Republic employees that held Bandwidth stock options began exercising their options. Upon exercise, Bandwidth withholds the employee tax amounts due from the proceeds. Bandwidth had collected on behalf of, and remitted withholding tax to, Republic of $9,213, $1,781, and $1,401 for the years ended December 31, 2018, 2019 and 2020 respectively. As of December 31, 2019 and December 31, 2020, the Company had no amounts were due to Republic. On September 30, 2019, the Company entered into a services agreement with Republic. Pursuant to the terms of the new agreement, Republic receives services performed by the Company’s legal department, effective September 30, 2019. The Company is compensated by Republic for these services based on costs incurred by the Company. The Company received net compensation under this agreement of $31 and $69 for the years ended December 31, 2019 and 2020, respectively, which is included in general and administrative expenses in the consolidated statements of operations. As of December 31, 2019 and December 31, 2020, the Company had a receivable of $10 and $2 under this agreement, respectively.

Basic and Diluted Income (Loss) per Common Share

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Basic and Diluted Income (Loss) per Common Share

17. Basic and Diluted Income (Loss) per Common Share

Basic net income (loss) per share is computed by dividing net income by the weighted-average number of shares of common stock outstanding during the period. Diluted net income (loss) per share is computed by giving effect to all potential shares of common stock, including stock options and stock related to unvested restricted stock awards.

The components of basic and diluted (loss) income per share are as follows:


	Year ended December 31,
		2018		2019		2020
Earnings per share


Net income (loss) attributable to common stockholders		$	17,923	$	2,494	$	(43,977)
Net income (loss) per share:
Basic		$	0.96	$	0.11	$	(1.83)
Diluted		$	0.85	$	0.10	$	(1.83)














Weighted Average Number of Common Shares Outstanding
Basic		18,573,067		22,640,461		24,092,574



Dilutive effect of stock options, restricted stock units, and warrants		2,567,315		1,283,316		—
Diluted		21,140,382		23,923,777		24,092,574

There were no common share equivalents with anti-dilutive effects for the years ended December 31, 2018 and 2019. The common share equivalents with anti-dilutive effects excluded from the weighted average shares used to calculate net loss per common share were 1,728,555, which consists of 255,000 stock options, 450,614 nonvested RSUs outstanding and 1,022,941 from convertible debt conversion for the year ended December 31, 2020.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Basis of Presentation

The consolidated financial statements and accompanying notes were prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”).

Reclassification

Principles of Consolidation

The consolidated financial statements include the accounts of Bandwidth Inc. and its wholly owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation.

Use of Estimates

Revenue Recognition

Adoption of Accounting Standards Codification (“ASC”) 606, “Revenue from Contracts with Customers”

Revenue Recognition Policy

Revenue recognition commences upon transfer of control of promised goods or services to customers in an amount that the Company expects to receive in exchange for those products or services.

The Company determines revenue recognition through the following steps:

•identification of the contract, or contracts, with a customer;

•identification of the performance obligations in the contract;

•determination of the transaction price;

•allocation of the transaction price to the performance obligations in the contract; and

•recognition of revenue, when, or as, the Company satisfies a performance obligation.

Nature of Products and Services

The remaining $3,215, $5,125 and $6,017 of CPaaS revenue for the years ended December 31, 2018, 2019 and 2020 respectively, are generated from other miscellaneous services.

Contract Assets and Liabilities

The following table provides information about receivables and contract liabilities from contracts with customers:


	As of December 31,
	2019		2020
Receivables (1)	$	30,187	$	55,243
Contract liabilities (2)	10,897		12,901

________________________

(1) Included in accounts receivable, net of allowance for doubtful accounts on the consolidated balance sheet.

(2) Included in current portion of deferred revenue and deferred revenue, net of current portion on the consolidated balance sheet.

Cost of Revenue

Research and Development

Research and DevelopmentResearch and development expenses consist primarily of personnel costs (including non-cash stock-based compensation expenses), outsourced software development and engineering services and cloud infrastructure fees for staging and development outsourced engineering services.

Sales and Marketing, General and Administrative

Sales and Marketing

General and Administrative

Cash and Cash Equivalents and Restricted Cash

Cash and Cash Equivalents

Restricted Cash

Accounts Receivable

Accounts Receivable and Current Expected Credit Losses

31, 2020. Refer to the Recently Adopted Accounting Standard section for the adoption of ASU 2019-11, Codification Improvements to Topic 326, Financial Instruments—Credit Losses for discussion of financial assets measured at amortized cost, including trade receivables.The Company includes unbilled receivables in its accounts receivable balance. Generally, these receivables represent services provided to customers, which will be billed in the next billing cycle. All amounts are considered collectible and billable.

Current Expected Credit Losses

Accounts Receivable and Current Expected Credit Losses

Concentration of Credit Risk

Property and Equipment, net


Computer hardware and software			1 to 7 years
Internal-use software development costs			4 to 7 years
Furniture and fixtures			2 to 5 years
Leasehold improvements			Shorter of the estimated lease term or 4 to 7 years

Maintenance and repairs are charged to expense as incurred.

Deferred Cost

Deferred Costs

Internal-Use Software Development Costs

costs incurred for maintenance and minor upgrades and enhancements. Costs related to preliminary project activities and post-implementation operating activities are expensed as incurred.

Debt Issuance Costs

Debt Issuance CostsThe Company incurred debt issuance costs associated with obtaining and entering into credit agreements. These costs customarily include non-refundable structuring fees, commitment fees, up-front fees and syndication expenses. The Company has a policy to defer and amortize these costs based on the effective interest method over the term of the credit agreements.

Goodwill

Impairment of Long-Lived Assets

Business Combinations

Advertising Costs

Advertising CostsThe Company expenses advertising costs as incurred.

Commissions

Share-Based Compensation

Stock-Based Compensation

Income Taxes

position. The Company recognizes potential accrued interest and penalties associated with unrecognized tax positions in income tax expense.

Operating Segments

Earnings Per Share

Earnings per Share

Foreign currency translation

The Company has foreign operations with non-USD functional currencies. The Euro and British Pound are the functional currencies for the Company’s international operations.

Fair Value of Financial Instruments

Comprehensive Income (Loss)

Recently Adopted Accounting Standards and Accounting Pronouncements Not Yet Adopted

Recently Adopted Accounting Standards

Recent Accounting Pronouncements Not Yet Adopted

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Schedule of Contract Assets and Liabilities

The following table provides information about receivables and contract liabilities from contracts with customers:


	As of December 31,
	2019		2020
Receivables (1)	$	30,187	$	55,243
Contract liabilities (2)	10,897		12,901

________________________

(1) Included in accounts receivable, net of allowance for doubtful accounts on the consolidated balance sheet.

(2) Included in current portion of deferred revenue and deferred revenue, net of current portion on the consolidated balance sheet.

Business Combination (Tables)

12 Months Ended

Dec. 31, 2020

Business Combinations [Abstract]

Aggregate Purchase Consideration

The aggregate purchase consideration has been preliminarily allocated as follows:


	Estimated fair value
Purchase Price:
Fair value of cash paid (1)	$	413,005
Fair value of Bandwidth common stock issued	106,379
Total purchase consideration	$	519,384

________________________

(1) Amount subject to adjustment upon finalization of the net working capital adjustment.

Aggregate Purchase Consideration Allocation


	Estimated fair value
Purchase Price Allocation:
Cash	$	4,360
Accounts receivable	5,873
Other current assets	3,315
Property and equipment	3,865
Intangible assets	232,600
Other non-current assets	3,418
Total current liabilities	(17,581)
Deferred tax liability	(58,149)
Other non-current liabilities	(4,881)
Net identifiable assets acquired	172,820
Goodwill	346,564
Net assets acquired	$	519,384

Estimated Preliminary Fair Value and Weighted Average Useful life of Identifiable Intangible Assets

The estimated preliminary fair value and weighted average useful life of the Voxbone identifiable intangible assets are as follows.


	Fair value		Weighted average useful life
			(In years)
Developed technology	$	84,100	10
Customer relationships	148,500		15
Preliminary fair value of identifiable intangible assets	$	232,600

Unaudited Pro Forma Information


	Year ended December 31,
	2019		2020
	(Unaudited)
Revenue	$	297,377	$	411,830
Net loss attributable to common stockholders	$	(7,737)	$	(42,675)

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Schedule of Assets Measured at Fair Value on a Recurring Basis

The following table summarizes the assets measured at fair value as of December 31, 2019 and December 31, 2020:


				Fair value measurements on a recurring basis December 31, 2019
	Level 1	Level 2	Level 3	Total
Financial assets:
Cash and cash equivalents:
Money market account				$	25,000	$	—	$	—	$	25,000
Time deposits				75,250		—		—		75,250










Total financial assets				$	100,250	$	—	$	—	$	100,250


				Fair value measurements on a recurring basis December 31, 2020
	Level 1	Level 2	Level 3			Total
Financial assets:
Cash and cash equivalents:
Money market account				$	57,517		$	—	$	—	$	57,517









Other investments:
Time deposits				40,000			—		—		40,000

Total financial assets				$	97,517		$	—	$	—	$	97,517

Financial Statement Components (Tables)

12 Months Ended

Dec. 31, 2020

Financial Statement Components [Abstract]

Schedule of Accounts Receivable, net, and Allowance for Doubtful Accounts

Accounts receivable, net of allowances consist of the following:


	As of December 31,
	2019		2020
Trade accounts receivable	$	14,692	$	26,504
Unbilled accounts receivable	16,200		27,692
Allowance for doubtful accounts and reserve for expected credit losses	(769)		(1,203)
Other accounts receivable	64		2,250
Total accounts receivable, net	$	30,187	$	55,243

Components of allowance for doubtful accounts and reserve for expected credit losses are as follows:


	Year ended December 31,
		2019		2020
Allowance for doubtful accounts:
Balance, beginning of period		$	(906)	$	(769)
Charged to bad debt expense		(1,543)		(1,322)
Deductions (1)		1,680		888



Balance, end of period		$	(769)	$	(1,203)

________________________

(1) Write off of uncollectible accounts after all collection efforts have been exhausted.

Schedule of Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following:


	As of December 31,
	2019		2020
Accrued expense	$	12,701	$	31,549
Accrued compensation and benefits	8,284		19,534
Accrued sales, use, VAT and telecommunications related taxes	5,439		9,142

Other accrued expenses	904		2,657
Current portion of finance lease	—		183
Total accrued expenses and other current liabilities	$	27,328	$	63,065

Right-of-Use Asset and Lease Liabilities (Tables)

12 Months Ended

Dec. 31, 2020

Leases [Abstract]

Schedule of Future Minimum Lease Receipts for Operating Lease

Future minimum sub-lease receipts required under the non-cancellable lease are as follows:


	As of December 31,
	2020

2021	$	457
2022	249


	$	706

Components of Lease Expense

The components of lease expense recorded in the consolidated statement of operations were as follows:


	Year ended December 31,
		2019		2020
Operating lease cost		$	5,548	$	5,949
Finance lease cost:
Amortization of assets		—		20
Interest on lease liabilities		—		2


Sublease income (1)		(643)		(384)
Total net lease cost		$	4,905	$	5,587

________________________

(1) See Note 16, “Related Parties” to these consolidated financial statements, for additional details on sublease income.

Supplemental cash flow and other information related to leases was as follows:


	Year ended December 31,
		2019			2020
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases		$	3,357		$	5,301

Financing cash flows from finance leases		—			28
		$	3,357		$	5,329

Weighted average remaining lease term (in years)
Operating leases		4.35			3.79
Finance leases		—			2.99

Weighted average discount rate
Operating leases		4.98		%	4.81		%
Finance leases		—		%	4.00		%

Supplemental Balance Sheet Lease Information

Supplemental balance sheet information related to leases was as follows:


		As of December 31,
Leases	Classification	2019		2020
Assets:
Operating lease assets	Operating right-of-use asset, net (1)	$	21,031	$	19,491
Finance lease assets	Property and equipment, net (2)	—		464
Total leased assets		$	21,031	$	19,955

Liabilities:
Current
Operating	Operating lease liability, current	$	4,876	$	5,515
Finance	Accrued expenses and other current liabilities	—		183
Non-current
Operating	Operating lease liability, net of current portion	19,868		17,202
Finance	Other liabilities	—		282
Total lease liabilities		$	24,744	$	23,182

________________________

(1) Operating lease assets are recorded net of accumulated amortization of $4,269 and $9,083 as of December 31, 2019 and December 31, 2020, respectively.

(2) Finance lease assets are recorded net of accumulated depreciation of $0 and $28 as of December 31, 2019 and December 31, 2020, respectively.

Schedule of Maturities of Operating Lease Liabilities

Maturities of operating lease liabilities were as follows:


	As of December 31,
	2020

2021	$	6,408
2022	6,755
2023	6,623
2024	2,701
2025	1,681
Thereafter	751
Total lease payments	24,919
Less: imputed interest	(2,202)
Less: accrued lease incentive	—
Total lease obligations	22,717
Less: current obligations	(5,515)
Long-term lease obligations	$	17,202

Schedule of Maturities of Finance Lease Liabilities

Maturities of financing lease liabilities were as follows:


	As of December 31,
	2020

2021	$	195
2022	146
2023	92
2024	55
2025	4

Total lease payments	492
Less: imputed interest	(27)

Total lease obligations	465
Less: current obligations	(183)
Long-term lease obligations	$	282

Asset Retirement Obligation

Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2020

Property, Plant and Equipment [Abstract]

Summary of Property and Equipment, Net

Property and equipment, net consisted of the following:


	As of December 31,
	2019		2020
Furniture and fixtures	$	2,373	$	2,341
Computer and office equipment	4,627		4,077
Telecommunications equipment	44,324		60,651
Leasehold improvements	5,263		6,285
Software	2,018		3,901
Internal-use software development	17,952		19,968
Automobile	10		502
Total cost	76,567		97,725
Less—accumulated depreciation	(34,913)		(46,080)
Total property and equipment, net	$	41,654	$	51,645

Schedule of Depreciation Expense

The Company recognized depreciation expense, which includes amortization of capitalized software development costs, as follows:


	Year ended December 31,
		2018		2019		2020
Cost of revenue		$	4,490	$	6,583	$	9,536
Research and development		161		268		670
Sales and marketing		51		112		120
General and administrative		568		2,055		2,811
Total depreciation expense		$	5,270	$	9,018	$	13,137

Goodwill and Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2020

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill

The changes in carrying amount of goodwill were as follows:


	Total
Balance as of December 31, 2019	$	6,867
Goodwill additions related to 2020 acquisition	346,564
Impact of foreign currency translation	18,808
Balance as of December 31, 2020	$	372,239

Schedule of Finite Lived Intangible Assets

Intangible assets, net consisted of the following as of December 31, 2019:


	Gross Amount		Accumulated Amortization		Net Carrying Value		Amortization Period
Dash acquisition and other intangibles:							(Years)
Customer relationships	$	10,396	$	(4,591)	$	5,805	20




Other, definite lived	3,933		(3,933)		—		2 - 7
Licenses, indefinite lived	764		—		764		Indefinite
Total intangible assets, net	$	15,093	$	(8,524)	$	6,569

Intangible assets, net consisted of the following as of December 31, 2020:


	Gross Amount		Accumulated Amortization		Net Carrying Value		Amortization Period
Dash acquisition and other intangibles:							(Years)
Customer relationships	$	10,396	$	(5,111)	$	5,285	20




Other, definite lived	3,933		(3,933)		—		2 - 7
Licenses, indefinite lived	764		—		764		Indefinite
Total Dash acquistion and other intangible assets	15,093		(9,044)		6,049

Voxbone acquistion:
Customer relationships	156,559		(1,739)		154,820		15
Developed technology	88,664		(1,478)		87,186		10
Total Voxbone acquisition	245,223		(3,217)		242,006

Total intangibles, net	$	260,316	$	(12,261)	$	248,055

Schedule of Infinite Lived Intangible Assets

Intangible assets, net consisted of the following as of December 31, 2019:


	Gross Amount		Accumulated Amortization		Net Carrying Value		Amortization Period
Dash acquisition and other intangibles:							(Years)
Customer relationships	$	10,396	$	(4,591)	$	5,805	20




Other, definite lived	3,933		(3,933)		—		2 - 7
Licenses, indefinite lived	764		—		764		Indefinite
Total intangible assets, net	$	15,093	$	(8,524)	$	6,569

Intangible assets, net consisted of the following as of December 31, 2020:


	Gross Amount		Accumulated Amortization		Net Carrying Value		Amortization Period
Dash acquisition and other intangibles:							(Years)
Customer relationships	$	10,396	$	(5,111)	$	5,285	20




Other, definite lived	3,933		(3,933)		—		2 - 7
Licenses, indefinite lived	764		—		764		Indefinite
Total Dash acquistion and other intangible assets	15,093		(9,044)		6,049

Voxbone acquistion:
Customer relationships	156,559		(1,739)		154,820		15
Developed technology	88,664		(1,478)		87,186		10
Total Voxbone acquisition	245,223		(3,217)		242,006

Total intangibles, net	$	260,316	$	(12,261)	$	248,055

Schedule of Future Estimated Amortization Expense

Future estimated amortization expense for definite lived intangible assets is as follows:


	As of December 31,
	2020

2021	$	19,824
2022	19,824
2023	19,824
2024	19,824
2025	19,824

Thereafter	148,171
	$	247,291

Debt (Tables)

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

Net Carrying Amount of Liability and Equity Component of Notes

The net carrying amount of the liability component of the Convertible Notes was as follows:


	As of December 31,
	2020
Principal	$	400,000
Unamortized discount	(110,546)
Unamortized debt issuance costs	(7,258)
Net carrying amount	$	282,196

The net carrying amount of the equity component of the Convertible Notes was as follows:


	As of December 31,
	2020
Proceeds allocated to the conversion options (debt discount)	$	125,152
Issuance costs	(3,742)
Net carrying amount	$	121,410

Interest Income and Interest Expense Disclosure

The following table sets forth the interest expense recognized related to the Convertible Notes:


	Year ended December 31,
		2020
Contractual interest expense		$	841
Amortization of debt discount		14,606
Amortization of debt issuance costs		959
Total interest expense related to the Convertible Notes		$	16,406

Segment and Geographic Information (Tables)

12 Months Ended

Dec. 31, 2020

Segment Reporting [Abstract]

Schedule of Segment Reporting Information, by Segment


	Year ended December 31,
		2018		2019		2020
CPaaS
Revenue		$	164,415	$	197,944	$	298,090
Cost of revenue		94,296		110,343		160,706
Gross profit		$	70,119	$	87,601	$	137,384
Other
Revenue		$	39,698	$	34,650	$	45,023
Cost of revenue		13,849		14,616		24,546
Gross profit		$	25,849	$	20,034	$	20,477
Consolidated
Revenue		$	204,113	$	232,594	$	343,113
Cost of revenue		108,145		124,959		185,252
Gross profit		$	95,968	$	107,635	$	157,861

Schedule of Revenue by Geographical Area

The Company generates its revenue primarily in the United States. Revenue by geographic area is detailed in the table below (which is determined based on the customer billing address):


	Year ended December 31,
		2018		2019		2020
CPaaS
United States		$	164,135	$	192,506	$	281,757
International		280		5,438		16,333
Total		$	164,415	$	197,944	$	298,090

Other
United States		$	39,432	$	33,664	$	42,692
International		266		986		2,331
Total		$	39,698	$	34,650	$	45,023

Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2020

Equity [Abstract]

Schedule of Reserved Shares of Common Stock for Issuance

The Company had reserved shares of Class A common stock for issuance under stock-based award agreements as follows:


	As of December 31,
	2019	2020
Stock options issued and outstanding	853,399	255,000
Nonvested restricted stock units issued and outstanding	392,351	450,614
Stock-based awards available for grant under the 2017 Plan	1,310,354	2,020,342
	2,556,104	2,725,956

- Definition

Tabular disclosure of an entity's stock, including par or stated value per share, number and dollar amount of share subscriptions, shares authorized, shares issued, shares outstanding, number and dollar amount of shares held in an employee trust, dividend per share, total dividends, share conversion features, par value plus additional paid in capital, the value of treasury stock and other information necessary to a fair presentation, and EPS information. Stock by class includes common, convertible, and preferred stocks which are not redeemable or redeemable solely at the option of the issuer. Includes preferred stock with redemption features that are solely within the control of the issuer and mandatorily redeemable stock if redemption is required to occur only upon liquidation or termination of the reporting entity. If more than one issue is outstanding, state the title of each issue and the corresponding dollar amount; dollar amount of any shares subscribed but unissued and the deduction of subscriptions receivable there from; number of shares authorized, issued, and outstanding.

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+ Details

Stock Based Compensation (Tables)

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Abstract]

Summary of Stock Option Activity

The following summarizes the stock option activity for the periods presented:


	Number of options outstanding	Weighted- average exercise price (per share)		Weighted- average remaining contract life (in years)	Aggregate intrinsic value (in thousands)
Outstanding as of December 31, 2019	853,399	$	8.07	3.41	$	47,770
Granted	—	—
Exercised	(593,084)	6.87			54,088
Forfeited or cancelled	(5,315)	10.30
Outstanding as of December 31, 2020	255,000	$	10.82	4.42	$	36,426

Options vested and exercisable at December 31, 2020	223,883	$	9.99	4.11	$	32,168
Options vested and expected to vest as of December 31, 2020	254,826	$	10.82	4.41	$	36,403

Summary of Restricted Stock Unit Activity

The following summarizes the RSU activity for the periods presented:


	Number of awards outstanding	Weighted-average grant date fair value (per share)
Nonvested RSUs as of December 31, 2019	392,351	$	35.22
Granted	234,653	73.86
Vested	(161,067)	44.42
Forfeited or cancelled	(15,323)	49.21
Nonvested RSUs as of December 31, 2020	450,614	$	51.58

Schedule of Stock-Based Compensation Expense

The Company recognized total stock-based compensation expense as follows:


	Year ended December 31,
		2018		2019		2020
Cost of revenue		$	114	$	211	$	208
Research and development		555		1,461		2,118
Sales and marketing		511		1,199		1,525
General and administrative (1)		2,159		3,755		6,030
Total		$	3,339	$	6,626	$	9,881

________________________

Employee Benefit Plan (Tables)

12 Months Ended

Dec. 31, 2020

Retirement Benefits [Abstract]

Schedule of Projected Benefit Obligation and Plan Assets Changes

The following table summarizes information for the pension plans:


	As of December 31,
	2020
Change in benefit obligation:
Benefit obligation at beginning of year	$	—
Service cost	75
Interest cost	3
Actuarial loss	15
Taxes, insurance premiums and administrative expenses	(9)
Acquisitions/plan mergers	3,980
Benefit obligation at end of year	$	4,064

Change in plan assets:
Fair value of plan assets at beginning of year	$	—
Return on plan assets	8
Actuarial loss	2
Employer contribution	57
Acquisitions/plan mergers	2,824
Taxes, insurance premiums and administrative expenses	(9)
Fair value of plan assets at end of year	2,882
Funded status, net liability	$	1,182

The following table presents the balance sheet location of the Company’s pension liability:


	As of December 31,
	2020
Other liabilities	$	1,182

Summary of Defined Benefit Plan With Accumulated Benefit Obligation in Excess of Plan Assets

The following table summarizes information for the Company's pension plans with an accumulated benefit obligation in excess of plan assets:


	As of December 31,
	2020
Projected benefit obligation	$	4,064
Accumulated benefit obligation	3,450
Fair value of plan assets	2,882

Summary of Accumulated Benefit Obligation in Excess of Plan Assets

Pretax amounts for net periodic benefit cost and other amounts included in other comprehensive income (loss) for the defined benefit pension plans consisted of the following components:


	Year ended December 31,
	2020
Service cost	$	75
Interest cost	3
Return on plan assets	(8)
Net periodic pension cost	70

Changes in plan assets and benefit obligations included in other comprehensive income (loss):
Change in net actuarial loss	17
Total (before tax effect)	17
Total recognized in net periodic benefit cost and included in other comprehensive income (loss)	$	87

Significant Pension Benefit Costs Assumptions

Significant assumptions used in determining benefit obligations and net periodic benefit cost are as follows:


	Year ended December 31,
	2020
Defined benefit obligations:
Discount rate	0.50	%
Rate of salary increase	4.07	%
Inflation	1.60	%

Defined benefit cost:
Discount rate	1.50	%
Rate of salary increase	4.37	%
Rate of return on plan assets	0.50	%
Inflation	1.90	%

Schedule of Major Categories of Plan Assets

The major categories of plan assets are as follows:


	As of December 31,
	2020
Assets held by:
Insurance companies (collective)	$	2,853
Insurance companies (individual)	29
Total	$	2,882

Estimated Future Pension and Postretirement Benefit Payments

The following table summarizes projected benefit payments from the Company's pension plans through 2030, including benefits attributable to estimated future service:


	As of December 31,
	2020
2021	$	5
2022	5
2023	5
2024	35
2025	5
2026-2030	37
	$	92

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Schedule of Domestic and Foreign Components of Income (Loss)

The following table presents domestic and foreign components of income (loss) before income taxes for the tax years ended December 31, 2018, 2019 and 2020:


	Year Ended December 31,
	2018		2019		2020
United States	$	7,053	$	(15,229)	$	(25,745)
International	—		5		(3,227)
Income (loss) before income taxes	$	7,053	$	(15,224)	$	(28,972)

Components of (Provision) Benefit for Income Taxes from Continuing Operations

Benefit (provision) for income taxes from operations consists of the following:


	Year Ended December 31,

	2018		2019		2020
Current:
Federal	$	162	$	81	$	431
State	(125)		132		(87)
Foreign	—		3		(1,083)
Total	37		216		(739)
Deferred:
Federal	8,945		15,205		(9,847)
State	1,888		2,297		(5,176)
Foreign	—		—		757
Total	10,833		17,502		(14,266)
Income tax benefit (provision)	$	10,870	$	17,718	$	(15,005)

Schedule of Effective Income Tax Rate Reconciliation

The following table presents a reconciliation of the statutory federal tax rate and the Company's effective tax rate for the years ended December 31, 2018, 2019 and 2020:


	Year Ended December 31,
	2018		2019		2020
Federal Tax Rate	21.0	%	21.0	%	21.0	%
State Tax Rate	6.3		3.1		2.0
Non-deductible expenses	1.7		(1.6)		(9.2)
Research credit	(13.6)		7.2		10.5
Stock-based compensation	(168.0)		88.6		46.8
Change in valuation allowance	—		—		(123.4)
Deferred tax rate change	(0.7)		(0.3)		0.2
Other	(0.8)		(1.6)		0.3
Total	(154.1)	%	116.4	%	(51.8)	%

Significant Components of Deferred Tax Assets and Liabilities

The following table presents the significant components of the Company’s net deferred tax assets:


	As of December 31,
	2019		2020
Deferred tax assets:
Allowance for doubtful accounts	$	97	$	134
Accrued liabilities	2,083		3,478
Operating lease liabilities	6,335		4,878
Deferred revenue	1,682		1,702

Stock-based compensation - deferred tax asset	2,109		1,968
OID	—		9,433
Tax credits	3,710		7,270
Net operating losses	30,835		47,385
Other deferred tax assets	90		2,207
Total deferred tax assets	46,941		78,455
Less: valuation allowance	—		(37,771)
Net deferred tax assets	46,941		40,684
Deferred tax liabilities:
Property and equipment	5,793		8,038
Goodwill	855		989
Intangibles	41		60,667
Operating lease assets	5,295		4,092
Debt	—		27,766
Other liability	96		137
Total deferred tax liabilities	12,080		101,689
Net deferred tax asset (liability)	$	34,861	$	(61,005)

Summary of Unrecognized Tax Benefits

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:


	Year Ended December 31,
	2019		2020
Unrecognized tax benefits—January 1,	$	1,046	$	1,398
Gross increases—tax positions in prior period	—		402
Gross decreases—tax positions in prior period	(15)		—
Gross increases—tax positions in current period	367		614


Unrecognized tax benefits—December 31,	$	1,398	$	2,414

Basic and Diluted Income (Loss) per Common Share (Tables)

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Schedule of Earnings Per Share, Basic and Diluted

The components of basic and diluted (loss) income per share are as follows:


	Year ended December 31,
		2018		2019		2020
Earnings per share


Net income (loss) attributable to common stockholders		$	17,923	$	2,494	$	(43,977)
Net income (loss) per share:
Basic		$	0.96	$	0.11	$	(1.83)
Diluted		$	0.85	$	0.10	$	(1.83)














Weighted Average Number of Common Shares Outstanding
Basic		18,573,067		22,640,461		24,092,574



Dilutive effect of stock options, restricted stock units, and warrants		2,567,315		1,283,316		—
Diluted		21,140,382		23,923,777		24,092,574

Organization and Description of Business (Details) $ / shares in Units, $ in Thousands		12 Months Ended
	Nov. 02, 2020 USD ($) shares	Dec. 31, 2020 USD ($) segment	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Oct. 30, 2020 $ / shares
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of operating segments \| segment		2
Number of reportable segments \| segment		2
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Cash consideration		$ 400,493	$ 0	$ 0
Voxbone S.A
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Cash consideration	$ 413,005
Holdback	$ 8,153
Voxbone S.A \| Class A common shares
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Equity consideration for Voxbone acquisition (in shares) \| shares	663,394
Share price (usd per share) \| $ / shares					$ 160.355

Summary of Significant Accounting Policies - Use of Estimates (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2020
Change in Accounting Estimate [Line Items]
Revenue		$ (343,113)	$ (232,594)	$ (204,113)
Cost of revenue		$ (185,252)	$ (124,959)	$ (108,145)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Change in Accounting Estimate [Line Items]
Revenue, remaining performance obligation, amount, expected timing of satisfaction, period	12 months	12 months
Estimated period of benefit for nonrefundable upfront fees
Change in Accounting Estimate [Line Items]
Revenue		$ 1,632
Cost of revenue	$ 104	$ 859
Estimated period of benefit for nonrefundable upfront fees \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Change in Accounting Estimate [Line Items]
Revenue, remaining performance obligation, amount, expected timing of satisfaction, period			3 years
Estimated period of benefit for nonrefundable upfront fees \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Change in Accounting Estimate [Line Items]
Revenue, remaining performance obligation, amount, expected timing of satisfaction, period					4 years
Estimated Useful Life for Internal-use Software Development
Change in Accounting Estimate [Line Items]
Revenue	$ 314

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details

Summary of Significant Accounting Policies - Revenue Recognition (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Concentration Risk [Line Items]
Stockholders' equity	$ 429,923	$ 270,090	$ 108,770	$ 76,711
Revenue	343,113	232,594	204,113
Revenue recognized related to its contract liabilities	3,599
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Concentration Risk [Line Items]
Revenue, remaining performance obligation, amount	$ 6,515
Revenue, remaining performance obligation, amount, expected timing of satisfaction, period	12 months
CPaaS, Usage-Based Fees
Concentration Risk [Line Items]
Revenue	$ 219,817	131,626	105,481
Other, Usage-Based Fees
Concentration Risk [Line Items]
Revenue	40,842	29,012	32,524
CPaaS, Service Fees
Concentration Risk [Line Items]
Revenue	72,256	61,193	55,719
Other, Service Fees
Concentration Risk [Line Items]
Revenue	4,181	5,638	7,174
Other miscellaneous services
Concentration Risk [Line Items]
Revenue	6,017	5,125	3,215
Adjustment to opening retained earnings due to adoption of ASC 606
Concentration Risk [Line Items]
Stockholders' equity			(174)
Retained earnings
Concentration Risk [Line Items]
Stockholders' equity	$ (49,505)	(5,528)	(7,848)	$ (25,771)
Retained earnings \| Adjustment to opening retained earnings due to adoption of ASC 606
Concentration Risk [Line Items]
Stockholders' equity		$ 174	$ (174)

Summary of Significant Accounting Policies - Schedule of Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Receivables	$ 55,243	$ 30,187
Contract liabilities	$ 12,901	$ 10,897

Summary of Significant Accounting Policies - Remaining Performance Obligation (Details) - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 $ in Thousands	Dec. 31, 2020 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 6,515
Revenue, remaining performance obligation, amount, expected timing of satisfaction, period	12 months

Summary of Significant Accounting Policies - Cash and Cash Equivalents and Accounts Receivable and Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
RRAs collateralized by deposits in form of Government Securities and Obligations as percentage of value	102.00%
Allowance for doubtful accounts	$ 1,203	$ 769
Unbilled accounts receivable	$ 27,692	$ 16,200

Summary of Significant Accounting Policies - Accounts Receivable and Current Expected Credit Losses and Concentration of Credit Risk and Deferred Revenue and Customer Deposits (Details)	12 Months Ended
	Dec. 31, 2020
Concentration Risk [Line Items]
Capitalized contract cost, amortization period	4 years
Customer One \| Accounts Receivable
Concentration Risk [Line Items]
Concentration risk percentage	11.00%

Summary of Significant Accounting Policies - Property and Equipment, net, Deferred Costs and Internal-Use Software Development Costs (Details)	3 Months Ended	6 Months Ended		12 Months Ended
	Dec. 31, 2020	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Capitalized contract cost, amortization period	4 years	4 years		4 years
Minimum
Property, Plant and Equipment [Line Items]
Capitalized contract cost, amortization period	4 years	4 years		4 years
Maximum
Property, Plant and Equipment [Line Items]
Capitalized contract cost, amortization period	7 years	7 years		7 years
Computer hardware and software \| Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life				1 year
Computer hardware and software \| Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	7 years
Internal-use software development costs
Property, Plant and Equipment [Line Items]
Property and equipment, useful life		4 years	3 years
Internal-use software development costs \| Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life				4 years
Internal-use software development costs \| Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life				7 years
Furniture and fixtures \| Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life				2 years
Furniture and fixtures \| Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life				5 years
Leasehold improvements \| Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life				4 years
Leasehold improvements \| Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life				7 years

Summary of Significant Accounting Policies - Goodwill, Advertising Costs, Stock-Based Compensation, Operating Segments, Foreign Currency Translation (Details)	12 Months Ended
	Dec. 31, 2020 USD ($) segment	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Accounting Policies [Abstract]
Number of reporting units \| segment	2
Goodwill	$ 372,239,000	$ 6,867,000
Goodwill impairment charges	0	0	$ 0
Advertising costs	$ 1,617,000	1,528,000	953,000
Service period	4 years
Number of operating segments \| segment	2
Number of reportable segments \| segment	2
Foreign currency transaction gain	$ 32,000	$ 9,000	$ 0

Summary of Significant Accounting Policies - Recently Adopted Accounting Standards (Details) $ in Thousands	Dec. 31, 2020 USD ($)
ASU 2018-15
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Capitalized implementation costs related to cloud computing arrangements	$ 572

Business Combination - Additional Information (Details) - Voxbone S.A $ / shares in Units, $ in Thousands		12 Months Ended
	Nov. 02, 2020 USD ($) segment shares	Dec. 31, 2020 USD ($)	Oct. 30, 2020 $ / shares
Business Acquisition [Line Items]
Total purchase consideration	$ 519,384
Accounts receivable	$ 5,873
Gross contractual amount		$ 6,453
Estimated uncollectible		580
Acquisition related costs		14,458
Revenues		17,541
Net loss		(3,112)
World gross domestic product voxbone operates (in percent)	93.00%
Number of countries Voxbone operates \| segment	60
General and administrative expenses
Business Acquisition [Line Items]
Acquisition related costs		12,675
Other expense
Business Acquisition [Line Items]
Acquisition related costs		$ 1,783
Common stock
Business Acquisition [Line Items]
Equity consideration for Voxbone acquisition (in shares) \| shares	663,394
Share price (usd per share) \| $ / shares			$ 160.355

Business Combination - Aggregate Purchase Consideration (Details) - USD ($) $ in Thousands		12 Months Ended
	Nov. 02, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Fair value of cash paid		$ 400,493	$ 0	$ 0
Voxbone S.A
Business Acquisition [Line Items]
Fair value of cash paid	$ 413,005
Total purchase consideration	519,384
Voxbone S.A \| Common stock
Business Acquisition [Line Items]
Fair value of Bandwidth common stock issued	$ 106,379

Business Combination - Purchase Price Allocation (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Nov. 02, 2020	Dec. 31, 2019
Purchase Price Allocation:
Goodwill	$ 372,239		$ 6,867
Voxbone S.A
Purchase Price Allocation:
Cash		$ 4,360
Accounts receivable		5,873
Other current assets		3,315
Property and equipment		3,865
Intangible assets		232,600
Other non-current assets		3,418
Total current liabilities		(17,581)
Deferred tax liability		(58,149)
Other non-current liabilities		(4,881)
Net identifiable assets acquired		172,820
Goodwill		346,564
Net assets acquired		$ 519,384

Business Combination - The Estimated Preliminary Fair Value And Weighted Average Useful Life (Details) - USD ($) $ in Thousands		12 Months Ended
	Nov. 02, 2020	Dec. 31, 2020
Business Acquisition [Line Items]
Weighted average useful life		13 years
Voxbone S.A
Business Acquisition [Line Items]
Fair value	$ 232,600
Voxbone S.A \| Developed technology
Business Acquisition [Line Items]
Fair value	$ 84,100
Weighted average useful life	10 years
Voxbone S.A \| Customer relationships
Business Acquisition [Line Items]
Fair value	$ 148,500
Weighted average useful life	15 years

Business Combination - The Unaudited Pro Forma Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Business Combinations [Abstract]
Revenue	$ 411,830	$ 297,377
Net loss attributable to common stockholders	$ (42,675)	$ (7,737)

Fair Value Measurements - Assets Measured at Fair Value (Details) - Fair value measurements on a recurring basis - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Money market account
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 57,517	$ 25,000
Time deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents		75,250
Other investments	40,000
Financial assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	97,517	100,250
Level 1 \| Money market account
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	57,517	25,000
Level 1 \| Time deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents		75,250
Other investments	40,000
Level 1 \| Financial assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	97,517	100,250
Level 2 \| Money market account
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Level 2 \| Time deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents		0
Other investments	0
Level 2 \| Financial assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	0	0
Level 3 \| Money market account
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Level 3 \| Time deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents		0
Other investments	0
Level 3 \| Financial assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	$ 0	$ 0

Fair Value Measurements - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Maturities of marketable securities	$ 0	$ 69,000	$ 18,000
Proceeds From Sale Of Marketable Securities		17,467
Gain on sale of marketable securities	0	4	0
Interest earned on marketable securities	0	$ 6	$ 77
Pension Plan
Debt Instrument [Line Items]
Fair value of plan assets	2,882
Convertible notes \| 0.25% convertible senior notes due 2026
Debt Instrument [Line Items]
Fair value	$ 716,250

Financial Statement Components - Accounts Receivable, Net of Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financial Statement Components [Abstract]
Trade accounts receivable	$ 26,504	$ 14,692
Unbilled accounts receivable	27,692	16,200
Allowance for doubtful accounts and reserve for expected credit losses	(1,203)	(769)
Other accounts receivable	2,250	64
Total accounts receivable, net	$ 55,243	$ 30,187

Financial Statement Components - Allowance For Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance, beginning of period	$ (769)	$ (906)
Charged to bad debt expense	(1,322)	(1,543)
Deductions	888	1,680
Balance, end of period	$ (1,203)	$ (769)

Financial Statement Components - Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financial Statement Components [Abstract]
Accrued expense	$ 31,549	$ 12,701
Accrued compensation and benefits	19,534	8,284
Accrued sales, use, VAT and telecommunications related taxes	9,142	5,439
Other accrued expenses	2,657	904
Current portion of finance lease	183	0	$ 183
Total accrued expenses and other current liabilities	$ 63,065	$ 27,328

Right-of-Use Asset and Lease Liabilities - Additional Information (Details) $ in Thousands	Dec. 31, 2020 USD ($) ft² segment
Lessee, Lease, Description [Line Items]
Office space (in square foot) \| ft²	17,073
Option to extend, term	5 years
Asset retirement obligation \| $	$ 240
Number of leases with early-termination option \| segment	1
Minimum
Lessee, Lease, Description [Line Items]
Remaining lease term	11 months
Maximum
Lessee, Lease, Description [Line Items]
Remaining lease term	6 years

Right-of-Use Asset and Lease Liabilities - Future Minimum Sub-lease Receipts (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Leases [Abstract]
2021	$ 457
2022	249
Total	$ 706

Right-of-Use Asset and Lease Liabilities - Components of Lease Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease cost	$ 5,949	$ 5,548
Amortization of assets	20	0
Interest on lease liabilities	2	0
Sublease income	(384)	(643)
Total net lease cost	5,587	4,905
Short-term operating lease expense	$ 199	$ 22

Right-of-Use Asset and Lease Liabilities - Supplemental Balance Sheet Lease Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Assets:
Operating lease assets	$ 19,491	$ 21,031
Finance lease assets	464	0
Total leased assets	19,955	21,031
Current
Operating	5,515	4,876
Finance	183	0	$ 183
Non-current
Operating	17,202	19,868
Long-term lease obligations	282	0
Total lease obligations	23,182	24,744
Right-of-use asset amortization	4,812	4,269	$ 0
Accumulated depreciation of the assets under finance leases	$ 28	$ 0
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:AccruedLiabilitiesCurrent	us-gaap:AccruedLiabilitiesCurrent
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent	us-gaap:OtherLiabilitiesNoncurrent
Accumulated amortization	$ 9,083	$ 4,269

Right-of-Use Asset and Lease Liabilities - Supplemental Cash Flow and Other Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases	$ 5,301	$ 3,357
Financing cash flows from finance leases	28	0	$ 92
Lease liabilities	$ 5,329	$ 3,357
Weighted average remaining lease term (in years)
Operating leases	3 years 9 months 14 days	4 years 4 months 6 days
Finance leases	2 years 11 months 26 days	0 years
Weighted average discount rate
Operating leases	4.81%	4.98%
Finance leases	4.00%	0.00%

Right-of-Use Asset and Lease Liabilities - Schedule of Maturities of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
2021	$ 6,408
2022	6,755
2023	6,623
2024	2,701
2025	1,681
Thereafter	751
Total lease payments	24,919
Less: imputed interest	(2,202)
Less: accrued lease incentive	0
Total lease obligations	22,717
Less: current obligations	(5,515)	$ (4,876)
Operating	$ 17,202	$ 19,868

Right-of-Use Asset and Lease Liabilities - Schedule of Maturities of Finance Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Leases [Abstract]
2021	$ 195
2022	146
2023	92
2024	55
2025	4
Total lease payments	492
Less: imputed interest	(27)
Total lease obligations	465
Less: current obligations	(183)	$ 0	$ (183)
Long-term lease obligations	$ 282	$ 0

Property and Equipment - Summary of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Total cost	$ 97,725	$ 76,567
Less—accumulated depreciation	(46,080)	(34,913)
Property and equipment, net	51,645	41,654
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total cost	2,341	2,373
Computer and office equipment
Property, Plant and Equipment [Line Items]
Total cost	4,077	4,627
Telecommunications equipment
Property, Plant and Equipment [Line Items]
Total cost	60,651	44,324
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total cost	6,285	5,263
Software
Property, Plant and Equipment [Line Items]
Total cost	3,901	2,018
Internal-use software development
Property, Plant and Equipment [Line Items]
Total cost	19,968	17,952
Automobile
Property, Plant and Equipment [Line Items]
Total cost	$ 502	$ 10

Property and Equipment - Additional Information (Details) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Unamortized software development costs	$ 5,957		$ 5,957	$ 5,746
Capitalized software development costs, additions			2,319	3,612	$ 2,028
Amortization of capitalized software development costs			1,963	2,024	1,482
Finance Lease, Right-of-Use Asset, before Accumulated Amortization	492		492
Accumulated depreciation of the assets under finance leases	$ 28		28	0
Capitalized software impairments			227	$ 275	$ 158
Internal-use software development
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	4 years	3 years
Prepaid expenses and other current assets
Property, Plant and Equipment [Line Items]
Capitalized implementation costs related to cloud computing arrangements	$ 144		144
Other long-term assets
Property, Plant and Equipment [Line Items]
Capitalized implementation costs related to cloud computing arrangements	$ 429		$ 429

Property and Equipment - Depreciation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Depreciation Expense [Line Items]
Total depreciation expense	$ 13,137	$ 9,018	$ 5,270
Cost of revenue
Depreciation Expense [Line Items]
Total depreciation expense	9,536	6,583	4,490
Research and development
Depreciation Expense [Line Items]
Total depreciation expense	670	268	161
Sales and marketing
Depreciation Expense [Line Items]
Total depreciation expense	120	112	51
General and administrative expenses
Depreciation Expense [Line Items]
Total depreciation expense	$ 2,811	$ 2,055	$ 568

Goodwill and Intangible Assets - Summary of Goodwill (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
Goodwill [Roll Forward]
Balance as of December 31, 2019	$ 6,867
Goodwill additions related to 2020 acquisition	346,564
Impact of foreign currency translation	18,808
Balance as of December 31, 2020	$ 372,239

Goodwill and Intangible Assets - Summary of Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Dash acquisition and other intangibles:
Accumulated amortization	$ 12,261
Finite-lived intangible assets, net	247,291
Gross Amount	260,316
Net Carrying Value	248,055	$ 6,569
Dash
Dash acquisition and other intangibles:
Accumulated amortization	(9,044)	(8,524)
Gross Amount	15,093	15,093
Net Carrying Value	6,049	6,569
Voxbone S.A
Dash acquisition and other intangibles:
Accumulated amortization	(3,217)
Gross Amount	245,223
Net Carrying Value	242,006
Licenses \| Dash
Dash acquisition and other intangibles:
Licenses, indefinite lived	764	764
Customer relationships \| Dash
Dash acquisition and other intangibles:
Finite-lived intangible assets, gross	10,396	10,396
Accumulated amortization	(5,111)	(4,591)
Finite-lived intangible assets, net	$ 5,285	$ 5,805
Amortization period	20 years	20 years
Customer relationships \| Voxbone S.A
Dash acquisition and other intangibles:
Finite-lived intangible assets, gross	$ 156,559
Accumulated amortization	(1,739)
Finite-lived intangible assets, net	$ 154,820
Amortization period	15 years
Other, definite lived \| Dash
Dash acquisition and other intangibles:
Finite-lived intangible assets, gross	$ 3,933	$ 3,933
Accumulated amortization	(3,933)	(3,933)
Finite-lived intangible assets, net	$ 0	$ 0
Other, definite lived \| Minimum \| Dash
Dash acquisition and other intangibles:
Amortization period	2 years	2 years
Other, definite lived \| Maximum \| Dash
Dash acquisition and other intangibles:
Amortization period	7 years	7 years
Developed technology \| Voxbone S.A
Dash acquisition and other intangibles:
Finite-lived intangible assets, gross	$ 88,664
Accumulated amortization	(1,478)
Finite-lived intangible assets, net	$ 87,186
Amortization period	10 years

Goodwill and Intangible Assets- Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense	$ 3,666	$ 520	$ 554
Weighted average useful life	13 years

Goodwill and Intangible Assets - Future Estimated Amortization Expense (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2021	$ 19,824
2022	19,824
2023	19,824
2024	19,824
2025	19,824
Thereafter	148,171
Finite-lived intangible assets, net	$ 247,291

Debt - Schedule of Debt (Details) - USD ($)		12 Months Ended
Debt - Schedule of Debt (Details) - USD ($)	Feb. 28, 2020	Dec. 31, 2020
Debt Disclosure [Abstract]
Principal		$ 400,000,000
Unamortized discount		(110,546,000)
Unamortized debt issuance costs		(7,258,000)
Net carrying amount		282,196,000
Proceeds allocated to the conversion options (debt discount)	$ 125,152,000	125,152,000
Issuance costs		(3,742,000)
Net carrying amount		$ 121,410,000

Debt - Interest Income and Interest Expense Disclosure (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
Debt Disclosure [Abstract]
Contractual interest expense	$ 841
Amortization of debt discount	14,606
Amortization of debt issuance costs	959
Total interest expense related to the Convertible Notes	$ 16,406

Debt - Additional Information (Details)			12 Months Ended
Debt - Additional Information (Details)	Feb. 28, 2020 USD ($) segment d $ / shares shares	Mar. 01, 2019 USD ($)	Dec. 31, 2020 USD ($) d $ / shares	Dec. 31, 2019 USD ($) $ / shares	Jun. 04, 2019 USD ($)
Debt Instrument [Line Items]
Debt instrument, term		3 years
Unamortized debt issuance costs			$ 83,000	$ 125,000
Debt outstanding			282,196,000
Principal			400,000,000
Total net proceeds	$ 344,722,000
Conversion price (usd per share) \| $ / shares	$ 91.03
Cash redemption price, percent	100.00%
Conversion option	$ 125,152,000		125,152,000
Effective interest rate	6.763%
Carrying amount of equity component	$ 57,485,000
Annual effective interest rate	6.907%
Issuance costs attributable to the liability component	$ 8,217,000
Issuance costs			$ (3,742,000)
Net cost of capped call purchase	$ 43,320,000
Conversion option 1
Debt Instrument [Line Items]
Trading days \| d	20		20
Consecutive trading days \| d	30		30
Conversion option 2
Debt Instrument [Line Items]
Consecutive trading days \| segment	10
Consecutive business days \| segment	5
Class A voting common stock
Debt Instrument [Line Items]
Conversion ratio	10.9857
Common stock, par value (in usd per share) \| $ / shares	$ 0.001		$ 0.001	$ 0.001
Capped call shares (in shares) \| shares	4,394,276
Class A voting common stock \| Conversion option 1
Debt Instrument [Line Items]
Stock price trigger percent	130.00%		130.00%
Class A voting common stock \| Conversion option 2
Debt Instrument [Line Items]
Stock price trigger percent	98.00%
Convertible notes \| 0.25% convertible senior notes due 2026
Debt Instrument [Line Items]
Principal	$ 400,000,000
Stated rate	0.25%
Convertible notes \| Capped call portion of 0.25% convertible senior notes due 2026
Debt Instrument [Line Items]
Conversion price (usd per share) \| $ / shares	$ 91.03
Convertible notes \| Capped call portion of 0.25% convertible senior notes due 2026 \| Maximum
Debt Instrument [Line Items]
Conversion price (usd per share) \| $ / shares	$ 137.40
Revolving Credit Facility
Debt Instrument [Line Items]
Borrowing capacity		$ 25,000,000	$ 25,000,000
Debt outstanding			0	$ 0
Available borrowing capacity			25,000,000
Revolving Credit Facility \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate		1.00%
Revolving Credit Facility \| Federal Funds Effective Rate
Debt Instrument [Line Items]
Basis spread on variable rate		0.50%
Revolving Credit Facility \| Pacific Western Bank
Debt Instrument [Line Items]
Borrowing capacity					$ 10,000,000
Revolving Credit Facility \| Key Bank National Association
Debt Instrument [Line Items]
Borrowing capacity					$ 15,000,000
Swing Line Of Credit
Debt Instrument [Line Items]
Borrowing capacity				1,000,000
Letters of credit
Debt Instrument [Line Items]
Borrowing capacity				2,500,000
Prepaid Expenses and Other Current Assets
Debt Instrument [Line Items]
Unamortized debt issuance costs			74,000	70,000
Other long-term assets
Debt Instrument [Line Items]
Unamortized debt issuance costs			$ 9,000	$ 55,000

Segment and Geographic Information - Reconciliation of Segment Profit (Loss) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) segment	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Segment Reporting [Abstract]
Number of reportable segments \| segment	2
Segment Reporting Information [Line Items]
Revenue	$ 343,113	$ 232,594	$ 204,113
Cost of revenue	185,252	124,959	108,145
Gross profit	157,861	107,635	95,968
CPaaS
Segment Reporting Information [Line Items]
Revenue	298,090	197,944	164,415
Cost of revenue	160,706	110,343	94,296
Gross profit	137,384	87,601	70,119
Other
Segment Reporting Information [Line Items]
Revenue	45,023	34,650	39,698
Cost of revenue	24,546	14,616	13,849
Gross profit	$ 20,477	$ 20,034	$ 25,849

- Definition

Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 31
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8924-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(ii))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 28
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=75031198&loc=d3e14064-108612

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1,2)
-URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Segment and Geographic Information - Reconciliation of Revenue by Geographic Area (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Assets	$ 890,608	$ 341,416
Revenue	343,113	232,594	$ 204,113
International
Revenues from External Customers and Long-Lived Assets [Line Items]
Assets	11,249	2,924
CPaaS
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	298,090	197,944	164,415
CPaaS \| United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	281,757	192,506	164,135
CPaaS \| International
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	16,333	5,438	280
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	45,023	34,650	39,698
Other \| United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	42,692	33,664	39,432
Other \| International
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 2,331	$ 986	$ 266

- Definition

Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(11))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(ii))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 28
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=75031198&loc=d3e14064-108612

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (bb)
-URI http://asc.fasb.org/extlink&oid=121559654&loc=d3e5710-111685

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=116870748&loc=SL6758485-165988

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(12))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8906-108599

Stockholders' Equity - Preferred Stock (Details) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Equity [Abstract]
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, par value (in usd per share)	$ 0.001	$ 0.001
Preferred stock, shares issued (in shares)	0	0
Preferred A stock, shares outstanding (in shares)	0	0

Stockholders' Equity - Common Stock (Details)	12 Months Ended
Stockholders' Equity - Common Stock (Details)	Dec. 31, 2020 vote $ / shares shares	Dec. 31, 2019 vote $ / shares shares	Dec. 31, 2018 $ / shares	Feb. 28, 2020 $ / shares
Class of Stock [Line Items]
Common stock, dividends declared (in usd per share) \| $ / shares	$ 0	$ 0	$ 0
Class A voting common stock
Class of Stock [Line Items]
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, par value (in usd per share) \| $ / shares	$ 0.001	$ 0.001		$ 0.001
Common stock voting rights \| vote	1	1
Common stock, shares issued (in shares)	22,413,004	18,584,478
Common stock, shares outstanding (in shares)	22,413,004	18,584,478
Class B voting common stock
Class of Stock [Line Items]
Common stock, shares authorized (in shares)	20,000,000	20,000,000
Common stock, par value (in usd per share) \| $ / shares	$ 0.001	$ 0.001
Common stock voting rights \| vote	10	10
Common stock, shares issued (in shares)	2,496,125	4,927,401
Common stock, shares outstanding (in shares)	2,496,125	4,927,401

Stockholders' Equity - Reserved Shares of Common Stock for Issuance (Details) - shares	Dec. 31, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	2,725,956	2,556,104
Stock options issued and outstanding
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	255,000	853,399
Nonvested restricted stock units issued and outstanding
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	450,614	392,351
Stock-based awards available for grant under the 2017 Plan
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	2,020,342	1,310,354

Stock Based Compensation - Additional Information (Details) - USD ($) $ in Thousands			12 Months Ended
	Jan. 01, 2020	Jan. 01, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Nov. 09, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)			2,725,956	2,556,104
Service period			4 years
Estimated grant date fair value of options vested			$ 416	$ 729	$ 979
Unrecognized cost for stock based compensation			$ 152
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of options, granted (in shares)			0
Unrecognized cost for stock based compensation, period for recognition (in years)			7 months 28 days
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)			450,614	392,351
Vesting percentage			25.00%
Service period			4 years
Unrecognized cost for stock based compensation, period for recognition (in years)			2 years 8 months 19 days
Unrecognized compensation cost related to non-vested RSUs			$ 18,319
Restricted Stock Units (RSUs) \| Non-employee Board of Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)			4 years
Restricted Stock Units (RSUs) \| Non-employee Board of Directors \| Year one vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			50.00%
Restricted Stock Units (RSUs) \| Non-employee Board of Directors \| First quarter vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			12.50%
Restricted Stock Units (RSUs) \| Non-employee Board of Directors \| Second quarter vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			12.50%
Restricted Stock Units (RSUs) \| Non-employee Board of Directors \| Third quarter vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			12.50%
Restricted Stock Units (RSUs) \| Non-employee Board of Directors \| First quarter vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			12.50%
Restricted Stock Units (RSUs) \| Non-employee Board of Directors \| Year two, three and four vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting percentage			50.00%
2017 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)						1,050,000
Common stock reserved for future issuance, percent increase		5.00%
Increase in shares available for grant (in shares)	929,224
Shares available for grant (in shares)			2,239,578
2017 Plan \| Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)			4 years
Contractual life (in years)			10 years

Stock Based Compensation - Stock Option Activity (Details) - Employee Stock Option - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Number of options outstanding
Number of options outstanding, beginning balance (in shares)	853,399
Number of options, granted (in shares)	0
Number of options exercised (in shares)	(593,084)
Number of options, forfeited or cancelled (in shares)	(5,315)
Number of options outstanding, ending balance (in shares)	255,000	853,399
Options vested and exercisable (in shares)	223,883
Options vested and expected to vest (in shares)	254,826
Weighted- average exercise price (per share)
Weighted-average exercise price, beginning balance (in usd per share)	$ 8.07
Weighted-average exercise price, granted (in usd per share)	0
Weighted-average exercise price, exercised (in usd per share)	6.87
Weighted-average exercise price, forfeited or cancelled (in usd per share)	10.30
Weighted-average exercise price, ending balance (in usd per share)	10.82	$ 8.07
Weighted-average exercise price, options vested and exercisable (in usd per share)	9.99
Weighted average exercise price, options vested and expected to vest (in usd per share)	$ 10.82
Weighted-average remaining contract life, options outstanding (in years)	4 years 5 months 1 day	3 years 4 months 28 days
Weighted-average remaining contract life, options vested and exercisable (in years)	4 years 1 month 9 days
Weighted average remaining contract life, options vested and expected to vest	4 years 4 months 28 days
Aggregate intrinsic value, options outstanding	$ 36,426	$ 47,770
Aggregate intrinsic value, options exercised	54,088
Aggregate intrinsic value, options vested and exercisable	32,168
Aggregate intrinsic value, options vested and expected to vest	$ 36,403

Stock Based Compensation - Restricted Stock Unit Activity (Details) - Restricted Stock Units (RSUs)	12 Months Ended
	Dec. 31, 2020 $ / shares shares
Number of awards outstanding
Number of nonvested RSUs outstanding, beginning balance (in shares) \| shares	392,351
Number of nonvested RSUs, granted (in shares) \| shares	234,653
Number of nonvested RSUs, vested (in shares) \| shares	(161,067)
Number of nonvested RSUs, forfeited or cancelled (in shares) \| shares	(15,323)
Number of nonvested RSUs outstanding, ending balance (in shares) \| shares	450,614
Weighted-average grant date fair value (per share)
Weighted-average grant date fair value, beginning balance (in usd per share) \| $ / shares	$ 35.22
Weighted average grant-date fair value of nonvested RSUs, granted (in usd per share) \| $ / shares	73.86
Weighted-average grant date fair value of nonvested RSUs, vested (in usd per share) \| $ / shares	44.42
Weighted-average grant date fair value of nonvested restricted RSUs, forfeited or cancelled (in usd per share) \| $ / shares	49.21
Weighted-average grant date fair value, ending balance (in usd per share) \| $ / shares	$ 51.58

Stock Based Compensation - Stock Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 21, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 9,881	$ 6,626	$ 3,339
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Number of nonvested RSUs outstanding (in shares)	450,614	392,351
Former employee \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Number of nonvested RSUs outstanding (in shares)				17,725
Cost of revenue
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 208	$ 211	114
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	2,118	1,461	555
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	1,525	1,199	511
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 6,030	$ 3,755	2,159
General and administrative \| Former employee \| Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense			$ 535

Commitments and Contingencies - Additional Information (Details) $ in Thousands			12 Months Ended
	Jun. 15, 2020 USD ($) a	Oct. 25, 2015 USD ($)	Dec. 31, 2020 USD ($)	Aug. 01, 2020 USD ($)	May 16, 2020 a
Lessee, Lease, Description [Line Items]
Service agreement, annual minimum commitments		$ 1,200
Service agreement, term of agreement (in years)		5 years
Annual minimum commitment, year one				$ 600
Annual minimum commitment, year two				$ 300
Non-cancellable purchase obligation			$ 13,378
Non-cancellable purchase obligation, fulfilled within a year			8,428
Land (acres) \| a	40				40
Maximum reimbursement of predevelopment work expenses			$ 597
Proposed
Lessee, Lease, Description [Line Items]
Consideration for the proposed Land purchase	$ 30,000
Maximum
Lessee, Lease, Description [Line Items]
Remaining lease term			6 years

Employee Benefit Plan - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Contribution Plan Disclosure [Line Items]
Matching contributions	$ 2,202	$ 1,731	$ 1,117
Pension Plan \| Non-U.S.
Defined Contribution Plan Disclosure [Line Items]
Accumulated benefit obligation	3,450
Expected contributions	$ 341

Employee Benefit Plan - Schedule of Projected Benefit Obligation and Plan Assets Changes (Details) - Pension Plan $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
Change in plan assets:
Fair value of plan assets at end of year	$ 2,882
Non-U.S.
Change in benefit obligation:
Benefit obligation at beginning of year	0
Service cost	75
Interest cost	3
Actuarial loss	15
Taxes, insurance premiums and administrative expenses	(9)
Acquisitions/plan mergers	3,980
Benefit obligation at end of year	4,064
Change in plan assets:
Fair value of plan assets at beginning of year	0
Return on plan assets	8
Actuarial loss	2
Employer contribution	57
Acquisitions/plan mergers	2,824
Fair value of plan assets at end of year	2,882
Funded status, net liability	1,182
Non-U.S. \| Other liabilities
Change in plan assets:
Other liabilities	$ (1,182)

Employee Benefit Plan - Summary of Accumulated Benefit Obligation in Excess of Plan Assets (Details) - Pension Plan - Non-U.S. $ in Thousands	Dec. 31, 2020 USD ($)
Defined Benefit Plan, Plan Assets, Category [Line Items]
Projected benefit obligation	$ 4,064
Accumulated benefit obligation	3,450
Fair value of plan assets	$ 2,882

Employee Benefit Plan - Summary of Net Periodic Cost of Pension and Postretirement Benefit Plans (Details) - Pension Plan - Non-U.S. $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 75
Interest cost	3
Return on plan assets	(8)
Net periodic pension cost	70
Changes in plan assets and benefit obligations included in other comprehensive income (loss):
Change in net actuarial loss	17
Total (before tax effect)	17
Total recognized in net periodic benefit cost and included in other comprehensive income (loss)	$ 87

Employee Benefit Plan - Significant Pension Benefit Costs Assumptions (Details)	12 Months Ended
	Dec. 31, 2020
Retirement Benefits [Abstract]
Discount rate	0.50%
Rate of salary increase	4.07%
Inflation	1.60%
Discount rate	1.50%
Rate of salary increase	4.37%
Rate of return on plan assets	0.50%
Inflation	1.90%

Employee Benefit Plan - Schedule of Major Categories of Plan Assets (Details) - Pension Plan - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	$ 2,882
Non-U.S.
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	2,882	$ 0
Insurance companies (collective) \| Non-U.S.
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	2,853
Insurance companies (individual) \| Non-U.S.
Defined Benefit Plan, Plan Assets, Category [Line Items]
Fair value of plan assets	$ 29

- Definition

Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

+ References + Details

Employee Benefit Plan - Estimated Future Pension and Postretirement Benefit Payments (Details) - Pension Plan - Non-U.S. $ in Thousands	Dec. 31, 2020 USD ($)
Defined Benefit Plan Disclosure [Line Items]
2021	$ 5
2022	5
2023	5
2024	35
2025	5
2026-2030	37
Net periodic pension cost	$ 92

Income Taxes - Schedule of Domestic and Foreign Components of Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
United States	$ (25,745)	$ (15,229)	$ 7,053
International	(3,227)	5	0
Income (loss) before income taxes	$ (28,972)	$ (15,224)	$ 7,053

Income Taxes - Components of (Provision) Benefit for Income Taxes from Continuing Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
Federal	$ 431	$ 81	$ 162
State	(87)	132	(125)
Foreign	(1,083)	3	0
Total	(739)	216	37
Deferred:
Federal	(9,847)	15,205	8,945
State	(5,176)	2,297	1,888
Foreign	757	0	0
Total	(14,266)	17,502	10,833
Income tax benefit (provision)	$ (15,005)	$ 17,718	$ 10,870

Income Taxes - Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Federal Tax Rate	21.00%	21.00%	21.00%
State Tax Rate	2.00%	3.10%	6.30%
Non-deductible expenses	(9.20%)	(1.60%)	1.70%
Research credit	10.50%	7.20%	(13.60%)
Stock-based compensation	46.80%	88.60%	(168.00%)
Change in valuation allowance	(123.40%)	0.00%	0.00%
Deferred tax rate change	0.20%	(0.30%)	(0.70%)
Other	0.30%	(1.60%)	(0.80%)
Total	(51.80%)	116.40%	(154.10%)

Income Taxes - Significant Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Allowance for doubtful accounts	$ 134	$ 97
Accrued liabilities	3,478	2,083
Operating lease liabilities	4,878	6,335
Deferred revenue	1,702	1,682
Stock-based compensation - deferred tax asset	1,968	2,109
OID	9,433	0
Tax credits	7,270	3,710
Net operating losses	47,385	30,835
Other deferred tax assets	2,207	90
Total deferred tax assets	78,455	46,941
Less: valuation allowance	(37,771)	0
Net deferred tax assets	40,684	46,941
Deferred tax liabilities:
Property and equipment	8,038	5,793
Goodwill	989	855
Intangibles	60,667	41
Operating lease assets	4,092	5,295
Debt	27,766	0
Other liability	137	96
Total deferred tax liabilities	101,689	12,080
Net deferred tax asset liability	$ (61,005)
Net deferred tax asset		$ 34,861

Income Taxes - Summary of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits, Beginning Balance	$ 1,398	$ 1,046
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions	402	0
Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions	0	(15)
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions	614	367
Unrecognized Tax Benefits, Ending Balance	$ 2,414	$ 1,398

Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
Federal tax credits	$ 9,653
Unrecognized tax benefits - beginning balance	2,414	$ 1,398	$ 1,046
Federal Ministry of Finance, Germany
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	187,385
Tax and Customs Administration, Netherlands
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	5,263
State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 125,334

Related Parties (Details) - Affiliated Entity - Republic - USD ($)		12 Months Ended
	Jun. 20, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Amount collected on behalf		$ 1,401,000	$ 1,781,000	$ 9,213,000
Facilities Sharing Agreement
Related Party Transaction [Line Items]
Reduction of rent expense		384,000	643,000	1,005,000
Due from related parties		0	0
Tax Sharing Agreement
Related Party Transaction [Line Items]
Due from related parties		0	0
Master Services Agreement
Related Party Transaction [Line Items]
Revenue from related parties		2,180,000	2,602,000	$ 3,884,000
Minimum monthly revenue expected from related party	$ 100,000
Minimum monthly revenue expected from related party, period	11 months
Accounts receivable, related parties		170,000	161,000
Services Agreement
Related Party Transaction [Line Items]
Revenue from related parties		69,000	31,000
Accounts receivable, related parties		$ 2,000	$ 10,000

Basic and Diluted Income (Loss) per Common Share - Components of Basic and Diluted Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Net income (loss) attributable to common stockholders	$ (43,977)	$ 2,494	$ 17,923
Net income (loss) per share:
Basic (in dollars per share)	$ (1.83)	$ 0.11	$ 0.96
Diluted (in dollars per share)	$ (1.83)	$ 0.10	$ 0.85
Weighted Average Number of Common Shares Outstanding
Basic (in shares)	24,092,574	22,640,461	18,573,067
Dilutive effect of stock options, restricted stock units, and warrants (in shares)	0	1,283,316	2,567,315
Diluted (in shares)	24,092,574	23,923,777	21,140,382

- Definition

The amount of net income (loss) from continuing operations per each share of common stock or unit outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22583-107794

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(19))
-URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

The amount of net income (loss) derived from continuing operations during the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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+ Details

Basic and Diluted Income (Loss) per Common Share - Schedule of Antidilutive Common Share Equivalents Excluded from Earnings Per Share (Details)	12 Months Ended
	Dec. 31, 2020 shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	1,728,555
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	255,000
Restricted Stock Units (RSUs)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	450,614
Convertible Debt Securities
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	1,022,941