we generate the substantial majority of our revenue from customers based on their usage of our software products that they have incorporated into their applications . in addition , customers typically purchase one or more telephone numbers from us , for which we charge a monthly flat fee per number . some customers also choose to purchase various levels of premium customer support for a monthly fee . customers that register in our self-service model typically pay up-front via credit card and draw down their balance as they purchase or use our products . most of our customers draw down their balance in the same month they pay up front and , as a result , our deferred revenue at any particular time is not a meaningful indicator of future revenue . as our customers ' usage grows , some of our customers enter into contracts and are invoiced monthly in arrears . many of these customer contracts have terms of 12 months and typically include some level of minimum revenue commitment . most customers with minimum revenue commitment contracts generate a significant amount of revenue in excess of their minimum revenue commitment in any period . historically , the aggregate minimum commitment revenue from customers with which we have contracts has constituted a minority of our revenue in any period , and we expect this to continue in the future . our developer-focused products are delivered to customers and users through our super network , which uses software to optimize communications on our platform . we interconnect with communications networks globally to deliver our products , and therefore we have arrangements with network service providers in many regions throughout the world . historically , a substantial majority of our cost of revenue has been network service provider fees . we continue to optimize our network service provider coverage and connectivity through continuous improvements in routing and sourcing in order to lower the usage expenses we incur for network service provider fees . as we benefit from our platform optimization efforts , we sometimes pass these savings on to customers in the form of lower usage prices on our products in an effort to drive increased usage and expand the reach and scale of our platform . in the near term , we intend to operate our business to expand the reach and scale of our platform and to grow our revenue , rather than to maximize our gross margins . we have achieved significant growth in recent periods . for the years ended december 31 , 2016 , 2015 and 2014 , our revenue was $ 277.3 million , $ 166.9 million and $ 88.8 million , respectively . in 2016 , 2015 and 2014 , our 10 largest active customer accounts generated an aggregate of 30 % , 32 % and 28 % , respectively . for the years ended december 31 , 2016 , 2015 and 2014 , among our 10 largest active customer accounts we had three , two and one variable customer accounts , respectively , representing 11 % , 17 % and 13 % , respectively . for the years ended december 31 , 2016 , 2015 and 2014 , our base revenue was $ 245.5 million , $ 136.9 million and $ 75.7 million , respectively . we incurred a net loss of $ 41.3 million , $ 35.5 million and $ 26.8 million for the years ended december 31 , 2016 , 2015 and 2014 , respectively . see the section titled `` key business metricsbase revenue `` for a discussion of base revenue . 61 initial public offering in june 2016 , we completed an initial public offering ( `` ipo `` ) in which we sold 11,500,000 shares of our newly authorized class a common stock , which included 1,500,000 shares sold pursuant to the exercise by the underwriters of an option to purchase additional shares , at the public offering price of $ 15.00 per share . we received net proceeds of $ 155.5 million , after deducting underwriting discounts and commissions and offering expenses paid by us , from the sale of our shares in the ipo . immediately prior to the completion of the ipo , all shares of common stock then outstanding were reclassified as shares of class b common stock and all shares of convertible preferred stock then outstanding were converted into 54,508,441 shares of common stock on a one-to-one basis , and then reclassified as shares of class b common stock . see note 12 to the consolidated financial statements included elsewhere in this annual report on form 10-k for further discussion of class a and b common stock . follow-on public offering in october 2016 , we completed a follow-on public offering in which we sold 1,691,222 shares of our class a common stock , which included 1,050,000 shares sold pursuant to the exercise by the underwriters of an option to purchase additional shares , at a public offering price of $ 40.00 per share . in addition , another 6,358,778 shares of our class a common stock were sold by our selling stockholders , which included 906,364 shares sold pursuant to the exercise of employee stock options by certain selling stockholders . we received aggregate proceeds of $ 64.4 million , after deducting underwriting discounts and commissions and estimated offering expenses paid and payable by us . story_separator_special_tag comparison of the fiscal years ended december 31 , 2016 , 2015 and 2014 revenue replace_table_token_14_th 2016 compared to 2015 in 2016 , base revenue increased by $ 108.7 million , or 79 % , compared to 2015 , and represented 89 % and 82 % of total revenue in 2016 and 2015 , respectively . this increase was primarily attributable to an increase in the usage of all our products , particularly our programmable messaging products and 68 programmable voice products , and the adoption of additional products by our existing customers . this increase was partially offset by pricing decreases that we have implemented over time for our customers in the form of lower usage prices in an effort to increase the reach and scale of our platform . the changes in usage and price in 2016 were reflected in our dollar-based net expansion rate of 161 % . the increase in usage was also attributable to a 44 % increase in the number of active customer accounts , from 25,347 as of december 31 , 2015 to 36,606 as of december 31 , 2016. in 2016 , variable revenue increased by $ 1.7 million , or 6 % , compared to 2015 , and represented 11 % and 18 % of total revenue in 2016 and 2015 , respectively . this increase was primarily attributable to the increase in the usage of products by our existing variable customer accounts , partially offset by the decrease in number of variable customer accounts from nine to eight . u.s. revenue and international revenue represented $ 233.9 million , or 84 % , and $ 43.4 million , or 16 % , respectively , of total revenue in 2016 , compared to $ 143.1 million , or 86 % , and $ 23.8 million , or 14 % , respectively , of total revenue in 2015. the increase in international revenue in absolute dollars and as a percentage of total revenue was attributable to the growth in usage of our products , particularly our programmable messaging products and programmable voice products , by our existing international active customer accounts and to a 61 % increase in the number of international active customer accounts , driven in part by our focus on expanding our sales to customers outside of the united states . we opened one office outside of the united states between december 31 , 2015 and december 31 , 2016 . 2015 compared to 2014 in 2015 , base revenue increased by $ 61.2 million , or 81 % , compared to 2014 , and represented 82 % and 85 % of total revenue in 2015 and 2014 , respectively . this increase was primarily attributable to an increase in the usage of all our products , particularly our programmable messaging products and programmable voice products , and the adoption of additional products by our existing customers . this increase was partially offset by pricing decreases that we have implemented over time for our customers in the form of lower usage prices in an effort to increase the reach and scale of our platform . the changes in usage and price in 2015 were reflected in our dollar-based net expansion rate of 155 % . the increase in usage was also attributable to a 52 % increase in the number of active customer accounts , from 16,631 as of december 31 , 2014 to 25,347 as of december 31 , 2015. in 2015 , variable revenue increased by $ 16.9 million , or 129 % , compared to 2014 , and represented 18 % and 15 % of total revenue in 2015 and 2014 , respectively . this increase was primarily attributable to the increase in the usage of products by our existing variable customer accounts . u.s. revenue and international revenue represented $ 143.1 million , or 86 % , and $ 23.8 million , or 14 % , respectively , of total revenue in 2015 , compared to $ 78.3 million , or 88 % , and $ 10.6 million , or 12 % , respectively , of total revenue in 2014. the increase in international revenue in absolute dollars and as a percentage of total revenue was attributable to the growth in usage of our products , particularly our programmable messaging products and programmable voice products , by our existing international active customer accounts and to a 78 % increase in the number of international active customer accounts , driven in part by our focus on expanding our sales to customers outside of the united states . we opened five offices outside of the united states between december 31 , 2014 and december 31 , 2015 . 69 cost of revenue and gross margin replace_table_token_15_th 2016 compared to 2015 in 2016 , cost of revenue increased by $ 46.1 million , or 62 % , compared to 2015. the increase in cost of revenue was primarily attributable to a $ 40.0 million increase in network service providers ' costs , a $ 2.8 million increase in cloud infrastructure fees to support the growth in usage of our products and a $ 1.9 million increase in amortization expense for internal-use software . in 2016 , gross margin improved primarily as a result of cost savings from our continued platform optimization efforts , along with changes in our product and geographic mix . 2015 compared to 2014 in 2015 , cost of revenue increased by $ 33.0 million , or 80 % , compared to 2014. the increase in cost of revenue was primarily attributable to a $ 28.6 million increase in network service providers ' costs , a $ 2.6 million increase in cloud infrastructure fees to support the growth in usage of our products and a $ 1.2 million increase in amortization expense for internal-use software . in 2015 , gross margin improved primarily as a result of cost savings from our continued platform optimization efforts

cash flows from operating activities in 2016 , cash provided by operating activities consisted primarily of our net loss of $ 41.3 million adjusted for non-cash items , including $ 24.2 million of stock-based compensation expense , $ 8.3 million of depreciation and amortization expense and $ 16.9 million of cumulative changes in operating assets and liabilities . with respect to changes in operating assets and liabilities , accounts payable and other liabilities increased $ 25.9 million and deferred revenue increased $ 4.1 million , which were primarily due to increases in transaction volumes and additional accruals of sales and other taxes . other long-term liabilities increased $ 9.1 million , primarily due to the increase in the deferred rent balance related to our new office lease in san francisco , california . this was partially offset by an increase in accounts receivable and prepaid expenses of $ 22.0 million , which primarily resulted from the growth of our business and the timing of cash receipts from certain of our larger customers , pre-payments for cloud infrastructure fees and certain operating expenses , and a $ 5.7 million net increase related to the tenant improvement allowance under our new san francisco , california office lease , after collecting $ 2.6 million from the landlord in the fourth quarter of 2016. in 2015 , cash used in operating activities consisted primarily of our net loss of $ 35.5 million adjusted for non-cash items , including $ 8.9 million of stock-based compensation expense , $ 4.2 million of depreciation and amortization expense and $ 2.9 million of cumulative changes in operating assets and liabilities . with respect to changes in operating assets and liabilities , accounts payable and other liabilities increased $ 13.9 million and deferred revenue increased $ 2.0 million , which were primarily due to increases in transaction volumes and additional accruals of sales and other taxes .


 Write a concise suspicious activity report of the following text delimited by triple backquotes. Return your response as a formal report which covers the key points highlighting the location,dates,entity names and account holder information in chronological order of the text.
     ```cash flows from operating activities in 2016 , cash provided by operating activities consisted primarily of our net loss of $ 41.3 million adjusted for non-cash items , including $ 24.2 million of stock-based compensation expense , $ 8.3 million of depreciation and amortization expense and $ 16.9 million of cumulative changes in operating assets and liabilities . with respect to changes in operating assets and liabilities , accounts payable and other liabilities increased $ 25.9 million and deferred revenue increased $ 4.1 million , which were primarily due to increases in transaction volumes and additional accruals of sales and other taxes . other long-term liabilities increased $ 9.1 million , primarily due to the increase in the deferred rent balance related to our new office lease in san francisco , california . this was partially offset by an increase in accounts receivable and prepaid expenses of $ 22.0 million , which primarily resulted from the growth of our business and the timing of cash receipts from certain of our larger customers , pre-payments for cloud infrastructure fees and certain operating expenses , and a $ 5.7 million net increase related to the tenant improvement allowance under our new san francisco , california office lease , after collecting $ 2.6 million from the landlord in the fourth quarter of 2016. in 2015 , cash used in operating activities consisted primarily of our net loss of $ 35.5 million adjusted for non-cash items , including $ 8.9 million of stock-based compensation expense , $ 4.2 million of depreciation and amortization expense and $ 2.9 million of cumulative changes in operating assets and liabilities . with respect to changes in operating assets and liabilities , accounts payable and other liabilities increased $ 13.9 million and deferred revenue increased $ 2.0 million , which were primarily due to increases in transaction volumes and additional accruals of sales and other taxes .
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 Suspicious Activity Report : we generate the substantial majority of our revenue from customers based on their usage of our software products that they have incorporated into their applications . in addition , customers typically purchase one or more telephone numbers from us , for which we charge a monthly flat fee per number . some customers also choose to purchase various levels of premium customer support for a monthly fee . customers that register in our self-service model typically pay up-front via credit card and draw down their balance as they purchase or use our products . most of our customers draw down their balance in the same month they pay up front and , as a result , our deferred revenue at any particular time is not a meaningful indicator of future revenue . as our customers ' usage grows , some of our customers enter into contracts and are invoiced monthly in arrears . many of these customer contracts have terms of 12 months and typically include some level of minimum revenue commitment . most customers with minimum revenue commitment contracts generate a significant amount of revenue in excess of their minimum revenue commitment in any period . historically , the aggregate minimum commitment revenue from customers with which we have contracts has constituted a minority of our revenue in any period , and we expect this to continue in the future . our developer-focused products are delivered to customers and users through our super network , which uses software to optimize communications on our platform . we interconnect with communications networks globally to deliver our products , and therefore we have arrangements with network service providers in many regions throughout the world . historically , a substantial majority of our cost of revenue has been network service provider fees . we continue to optimize our network service provider coverage and connectivity through continuous improvements in routing and sourcing in order to lower the usage expenses we incur for network service provider fees . as we benefit from our platform optimization efforts , we sometimes pass these savings on to customers in the form of lower usage prices on our products in an effort to drive increased usage and expand the reach and scale of our platform . in the near term , we intend to operate our business to expand the reach and scale of our platform and to grow our revenue , rather than to maximize our gross margins . we have achieved significant growth in recent periods . for the years ended december 31 , 2016 , 2015 and 2014 , our revenue was $ 277.3 million , $ 166.9 million and $ 88.8 million , respectively . in 2016 , 2015 and 2014 , our 10 largest active customer accounts generated an aggregate of 30 % , 32 % and 28 % , respectively . for the years ended december 31 , 2016 , 2015 and 2014 , among our 10 largest active customer accounts we had three , two and one variable customer accounts , respectively , representing 11 % , 17 % and 13 % , respectively . for the years ended december 31 , 2016 , 2015 and 2014 , our base revenue was $ 245.5 million , $ 136.9 million and $ 75.7 million , respectively . we incurred a net loss of $ 41.3 million , $ 35.5 million and $ 26.8 million for the years ended december 31 , 2016 , 2015 and 2014 , respectively . see the section titled `` key business metricsbase revenue `` for a discussion of base revenue . 61 initial public offering in june 2016 , we completed an initial public offering ( `` ipo `` ) in which we sold 11,500,000 shares of our newly authorized class a common stock , which included 1,500,000 shares sold pursuant to the exercise by the underwriters of an option to purchase additional shares , at the public offering price of $ 15.00 per share . we received net proceeds of $ 155.5 million , after deducting underwriting discounts and commissions and offering expenses paid by us , from the sale of our shares in the ipo . immediately prior to the completion of the ipo , all shares of common stock then outstanding were reclassified as shares of class b common stock and all shares of convertible preferred stock then outstanding were converted into 54,508,441 shares of common stock on a one-to-one basis , and then reclassified as shares of class b common stock . see note 12 to the consolidated financial statements included elsewhere in this annual report on form 10-k for further discussion of class a and b common stock . follow-on public offering in october 2016 , we completed a follow-on public offering in which we sold 1,691,222 shares of our class a common stock , which included 1,050,000 shares sold pursuant to the exercise by the underwriters of an option to purchase additional shares , at a public offering price of $ 40.00 per share . in addition , another 6,358,778 shares of our class a common stock were sold by our selling stockholders , which included 906,364 shares sold pursuant to the exercise of employee stock options by certain selling stockholders . we received aggregate proceeds of $ 64.4 million , after deducting underwriting discounts and commissions and estimated offering expenses paid and payable by us . story_separator_special_tag comparison of the fiscal years ended december 31 , 2016 , 2015 and 2014 revenue replace_table_token_14_th 2016 compared to 2015 in 2016 , base revenue increased by $ 108.7 million , or 79 % , compared to 2015 , and represented 89 % and 82 % of total revenue in 2016 and 2015 , respectively . this increase was primarily attributable to an increase in the usage of all our products , particularly our programmable messaging products and 68 programmable voice products , and the adoption of additional products by our existing customers . this increase was partially offset by pricing decreases that we have implemented over time for our customers in the form of lower usage prices in an effort to increase the reach and scale of our platform . the changes in usage and price in 2016 were reflected in our dollar-based net expansion rate of 161 % . the increase in usage was also attributable to a 44 % increase in the number of active customer accounts , from 25,347 as of december 31 , 2015 to 36,606 as of december 31 , 2016. in 2016 , variable revenue increased by $ 1.7 million , or 6 % , compared to 2015 , and represented 11 % and 18 % of total revenue in 2016 and 2015 , respectively . this increase was primarily attributable to the increase in the usage of products by our existing variable customer accounts , partially offset by the decrease in number of variable customer accounts from nine to eight . u.s. revenue and international revenue represented $ 233.9 million , or 84 % , and $ 43.4 million , or 16 % , respectively , of total revenue in 2016 , compared to $ 143.1 million , or 86 % , and $ 23.8 million , or 14 % , respectively , of total revenue in 2015. the increase in international revenue in absolute dollars and as a percentage of total revenue was attributable to the growth in usage of our products , particularly our programmable messaging products and programmable voice products , by our existing international active customer accounts and to a 61 % increase in the number of international active customer accounts , driven in part by our focus on expanding our sales to customers outside of the united states . we opened one office outside of the united states between december 31 , 2015 and december 31 , 2016 . 2015 compared to 2014 in 2015 , base revenue increased by $ 61.2 million , or 81 % , compared to 2014 , and represented 82 % and 85 % of total revenue in 2015 and 2014 , respectively . this increase was primarily attributable to an increase in the usage of all our products , particularly our programmable messaging products and programmable voice products , and the adoption of additional products by our existing customers . this increase was partially offset by pricing decreases that we have implemented over time for our customers in the form of lower usage prices in an effort to increase the reach and scale of our platform . the changes in usage and price in 2015 were reflected in our dollar-based net expansion rate of 155 % . the increase in usage was also attributable to a 52 % increase in the number of active customer accounts , from 16,631 as of december 31 , 2014 to 25,347 as of december 31 , 2015. in 2015 , variable revenue increased by $ 16.9 million , or 129 % , compared to 2014 , and represented 18 % and 15 % of total revenue in 2015 and 2014 , respectively . this increase was primarily attributable to the increase in the usage of products by our existing variable customer accounts . u.s. revenue and international revenue represented $ 143.1 million , or 86 % , and $ 23.8 million , or 14 % , respectively , of total revenue in 2015 , compared to $ 78.3 million , or 88 % , and $ 10.6 million , or 12 % , respectively , of total revenue in 2014. the increase in international revenue in absolute dollars and as a percentage of total revenue was attributable to the growth in usage of our products , particularly our programmable messaging products and programmable voice products , by our existing international active customer accounts and to a 78 % increase in the number of international active customer accounts , driven in part by our focus on expanding our sales to customers outside of the united states . we opened five offices outside of the united states between december 31 , 2014 and december 31 , 2015 . 69 cost of revenue and gross margin replace_table_token_15_th 2016 compared to 2015 in 2016 , cost of revenue increased by $ 46.1 million , or 62 % , compared to 2015. the increase in cost of revenue was primarily attributable to a $ 40.0 million increase in network service providers ' costs , a $ 2.8 million increase in cloud infrastructure fees to support the growth in usage of our products and a $ 1.9 million increase in amortization expense for internal-use software . in 2016 , gross margin improved primarily as a result of cost savings from our continued platform optimization efforts , along with changes in our product and geographic mix . 2015 compared to 2014 in 2015 , cost of revenue increased by $ 33.0 million , or 80 % , compared to 2014. the increase in cost of revenue was primarily attributable to a $ 28.6 million increase in network service providers ' costs , a $ 2.6 million increase in cloud infrastructure fees to support the growth in usage of our products and a $ 1.2 million increase in amortization expense for internal-use software . in 2015 , gross margin improved primarily as a result of cost savings from our continued platform optimization efforts

