44 financial overview financial results we reported losses from operations of approximately $ 55 million for 2017 , $ 14 million for 2016 and $ 31 million for 2015. we reported net losses of approximately $ 35 million for 2017 , $ 14 million for 2016 and $ 32 million for 2015. our revenue was approximately $ 330 million in 2017 , $ 253 million in 2016 and $ 249 million in 2015. our gross profit was approximately $ 201 million in 2017 , $ 168 million in 2016 and $ 162 million in 2015. our gross profit as a percentage of revenue ( `` total gross margin `` ) was approximately 61 % in 2017 , 66 % in 2016 and 65 % in 2015. our operating expenses were approximately $ 257 million in 2017 , compared to approximately $ 181 million in 2016 and approximately $ 193 million in 2015. our 2017 operating expenses included approximately $ 15 million of acquisition- and integration-related expenses , nearly all related to the merger , and approximately $ 9 million of restructuring expense . our 2017 restructuring expense was primarily related to severance and related costs . our 2016 operating expenses included approximately $ 1 million of acquisition- and integration-related costs for professional and services fees related to our acquisition of taqua and approximately $ 3 million of restructuring expense , primarily comprised of approximately $ 2 million related to our 2016 restructuring initiative and approximately $ 1 million related to our taqua restructuring initiative . our 2015 operating expenses included approximately $ 2 million of restructuring expense , comprised of approximately $ 4 million of expense related to our 2015 restructuring initiative , net of approximately $ 2 million of reversals of restructuring expense previously recorded in connection with our 2012 restructuring initiative . we recorded stock-based compensation expense of approximately $ 26 million in 2017 , $ 20 million in 2016 and $ 22 million in 2015. the expense recorded in 2017 includes approximately $ 9 million of incremental expense related to the acceleration of stock options and certain full value stock awards in connection with the merger . see `` results of operations `` in this management 's discussion and analysis of financial condition and results of operations ( `` md & a `` ) for additional discussion of our results of operations for the years ended december 31 , 2017 , 2016 and 2015. restructuring and cost reduction initiatives in connection with the merger , we implemented a restructuring plan in the fourth quarter of 2017 to eliminate certain redundant positions and facilities within the combined companies ( the `` merger restructuring initiative `` ) . accordingly , we recorded $ 8.5 million of restructuring expense in 2017 related to the merger restructuring initiative . we believe that the payments related to the amount accrued at december 31 , 2017 will be completed in 2018. we anticipate that we will record additional future expense in connection with this initiative for headcount and redundant facilities aggregating approximately $ 12 million . we believe that the payments related to this expected additional future expense will be completed by early 2019. we assumed genband 's restructuring liability aggregating approximately $ 4 million at the merger date ( the `` genband restructuring initiative `` ) , primarily related to headcount reductions . we do not expect to record additional expense in connection with this initiative except for adjustments for changes in estimated costs . we expect that the payments related to this assumed liability will be completed in 2018. in connection with the acquisition of taqua , we implemented a restructuring plan in the third quarter of 2016 to eliminate certain redundant positions within the combined companies . on october 24 , 2016 , the audit committee of our board of directors ( the `` audit committee `` ) approved a broader taqua restructuring plan related to headcount and redundant facilities ( collectively , the `` taqua restructuring initiative `` ) . in connection with this initiative , we have recorded approximately $ 2 million of restructuring expense for severance and related costs and estimated costs related to the elimination of redundant facilities , including adjustments recorded for changes in cost estimates for the planned restructuring activities . the actions under the taqua restructuring initiative have been implemented and accordingly , we do not expect to record additional expense in connection with this initiative . the amounts accrued for severance and related costs were fully paid by the end of the third quarter of 2017. we expect that the amounts accrued for facilities costs will be paid by the end of 2018 . 45 on july 25 , 2016 , we announced a program ( the `` 2016 restructuring initiative `` ) to further accelerate our investment in new technologies as the communications industry migrates to a cloud-based architecture and pursues new strategic initiatives , such as new products and an expanded go-to-market footprint in selected geographies and discrete vertical markets . we have recorded an aggregate of approximately $ 2 million of restructuring expense in connection with this initiative , primarily for severance and related costs . the amounts accrued for severance and related costs were fully paid by the end of the third quarter of 2017. we expect that the amounts accrued for facilities will be paid by the end of october 2019. to better align our cost structure to our then-current revenue expectations , in april 2015 , we announced a cost reduction review . on april 16 , 2015 , we initiated a restructuring plan to reduce our workforce by approximately 150 positions , or approximately 13 % of our worldwide workforce ( the `` 2015 restructuring initiative `` ) . we recorded nominal restructuring expense in 2016 and approximately $ 4 million in 2015 in connection with the 2015 restructuring initiative . story_separator_special_tag subsidiaries as of december 31 , 2017 , with the exception of the company 's irish subsidiary , as we do not plan to permanently reinvest these amounts outside the united states . the repatriation of the undistributed earnings would result in withholding taxes imposed on the repatriation . consequently , we have recorded a tax liability of $ 3.2 million , consisting primarily of withholding and distribution taxes , relating to undistributed earnings from these subsidiaries as of december 31 , 2017. had the earnings of the irish subsidiary been determined to not be permanently reinvested outside the u.s. , no additional deferred tax liability would be required due to no withholding taxes or income tax expense being imposed on such repatriation . we assess all material positions taken in any income tax return , including all significant uncertain positions , in all tax years that are still subject to assessment or challenge by relevant taxing authorities . assessing an uncertain tax position begins with the initial determination of the position 's sustainability and is measured at the largest amount of benefit that has a greater than 50 % likelihood of being realized upon ultimate settlement . as of each balance sheet date , unresolved uncertain tax positions must be reassessed , and we will determine whether ( i ) the factors underlying the sustainability assertion have changed and ( ii ) the amount of recognized tax benefit is still appropriate . the recognition and measurement of tax benefits require significant judgment . judgments concerning the recognition and measurement of a tax benefit might change as new information becomes available . on december 22 , 2017 , the u.s. government enacted comprehensive tax legislation commonly referred to as the tax cuts and jobs act ( the `` tax act `` ) . the tax act makes broad and complex changes to the u.s. tax code , including , but not limited to : reducing the u.s. federal corporate tax rate from 35 % to 21 % ; requiring companies to pay a one-time transition tax on certain unrepatriated earnings of foreign subsidiaries ; generally eliminating u.s. federal income taxes on dividends from foreign subsidiaries ; requiring a current inclusion in u.s. federal taxable income of certain earnings ( global intangible low-taxed income ) of controlled foreign corporation ; eliminating the corporate alternative minimum tax ( `` amt `` ) and changing how existing amt credits can be realized ; creating the base erosion anti-abuse tax ; creating a new limitation on deductible interest expense ; changing rules related to uses and limitations of net operating loss carryforwards created in tax years beginning after december 31 , 2017 ; providing a tax deduction for foreign-derived intangible income ; and changing rules related to deductibility of compensation for certain officers . the impact of certain effects of the tax act has been recognized in the period in which the new legislation was enacted per guidance in staff accounting bulletin 118 , which allows for a measurement period to complete the accounting for certain elements of the tax reform . we have not yet completed a full evaluation of the impact of the tax act on our financial statements , however , we have provided a reasonable estimate for the impact related to remeasured deferred tax assets based on the new federal income tax rate of 21 % . we have also provided for the provisional impact related to the tax act 's change to the federal nol and amt carryovers . the total estimated impact of $ 5 million is reflected in income from continuing operations , and increased the tax benefit for the year ended december 31 , 2017. we will continue to make and refine our calculations as 49 additional analysis is completed . we can not predict with certainty how the tax act will affect the company 's financial position or results of operations . results of operations years ended december 31 , 2017 and 2016 revenue . revenue for the years ended december 31 , 2017 and 2016 was as follows ( in millions , except percentages ) : replace_table_token_6_th product revenue is comprised of sales of our network transformation , security and applications solutions . the increase in product revenue in 2017 compared to 2016 was primarily the result of the inclusion genband 's product revenue approximating $ 38 million for the period since the merger date , approximately $ 20 million of higher sales of our security and application products and the inclusion of approximately $ 4 million of 2017 product revenue from taqua . these increases were partially offset by net decreases in sales of certain other products , primarily our legacy gateway products . in 2017 , approximately 24 % of our product revenue was from indirect sales through our channel partner program , compared to approximately 26 % in 2016. in 2017 , approximately 20 % of our product revenue was attributable to sales to enterprise customers , compared to approximately 19 % in 2016. these sales were made through both our direct sales team and indirect sales channel partners . the timing of the completion of customer projects , revenue recognition criteria satisfaction and customer payments may cause our product revenue to fluctuate from one period to the next . service revenue is primarily comprised of hardware and software maintenance and support ( “ maintenance revenue ” ) and network design , installation and other professional services ( “ professional services revenue ” ) . service revenue for the years ended december 31 , 2017 and 2016 was comprised of the following ( in millions , except percentages ) : replace_table_token_7_th our maintenance revenue increased in 2017 compared to 2016 primarily due to the inclusion of approximately $ 21 million of revenue attributable to genband in 2017 for the period since the merger date and the inclusion of approximately $ 5 million of revenue attributable to taqua . the increase in

of cash . our investing activities provided approximately $ 21 million of cash in 2017 and used approximately $ 27 million of cash in 2016. in 2017 , net sales of our investments in marketable securities provided approximately $ 67 million of cash , of which we used approximately $ 43 million to pay the cash consideration for genband . we used approximately $ 4 million to purchase property and equipment . in 2016 , we used approximately $ 21 million of cash , net of cash acquired , for business acquisitions , approximately $ 5 million of cash used for the purchase of property and equipment and approximately $ 3 million for net investments in marketable securities . the amount used for business acquisitions was comprised of $ 20 million , net of cash acquired , for the acquisition of taqua and slightly under $ 1 million paid as the final consideration installment for the sdn business . our financing activities used approximately $ 4 million of cash in 2017 and approximately $ 10 million of cash in 2016. the 2017 amount was primarily comprised of approximately $ 8 million used to pay withholding obligations related to the net share settlement of restricted and performance-based stock grants upon vesting and $ 1 million to pay debt issuance costs related to our credit agreement , partially offset by approximately $ 2 million of net borrowings against our credit agreement , $ 1 million of proceeds from the sale of our common stock in connection with our amended and restated 2000 employee stock purchaseplan , as amended ( `` espp '' ) and approximately $ 1 million of proceeds from the exercise of stock options .


 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.
     ```of cash . our investing activities provided approximately $ 21 million of cash in 2017 and used approximately $ 27 million of cash in 2016. in 2017 , net sales of our investments in marketable securities provided approximately $ 67 million of cash , of which we used approximately $ 43 million to pay the cash consideration for genband . we used approximately $ 4 million to purchase property and equipment . in 2016 , we used approximately $ 21 million of cash , net of cash acquired , for business acquisitions , approximately $ 5 million of cash used for the purchase of property and equipment and approximately $ 3 million for net investments in marketable securities . the amount used for business acquisitions was comprised of $ 20 million , net of cash acquired , for the acquisition of taqua and slightly under $ 1 million paid as the final consideration installment for the sdn business . our financing activities used approximately $ 4 million of cash in 2017 and approximately $ 10 million of cash in 2016. the 2017 amount was primarily comprised of approximately $ 8 million used to pay withholding obligations related to the net share settlement of restricted and performance-based stock grants upon vesting and $ 1 million to pay debt issuance costs related to our credit agreement , partially offset by approximately $ 2 million of net borrowings against our credit agreement , $ 1 million of proceeds from the sale of our common stock in connection with our amended and restated 2000 employee stock purchaseplan , as amended ( `` espp '' ) and approximately $ 1 million of proceeds from the exercise of stock options .
```    
 Suspicious Activity Report : 44 financial overview financial results we reported losses from operations of approximately $ 55 million for 2017 , $ 14 million for 2016 and $ 31 million for 2015. we reported net losses of approximately $ 35 million for 2017 , $ 14 million for 2016 and $ 32 million for 2015. our revenue was approximately $ 330 million in 2017 , $ 253 million in 2016 and $ 249 million in 2015. our gross profit was approximately $ 201 million in 2017 , $ 168 million in 2016 and $ 162 million in 2015. our gross profit as a percentage of revenue ( `` total gross margin `` ) was approximately 61 % in 2017 , 66 % in 2016 and 65 % in 2015. our operating expenses were approximately $ 257 million in 2017 , compared to approximately $ 181 million in 2016 and approximately $ 193 million in 2015. our 2017 operating expenses included approximately $ 15 million of acquisition- and integration-related expenses , nearly all related to the merger , and approximately $ 9 million of restructuring expense . our 2017 restructuring expense was primarily related to severance and related costs . our 2016 operating expenses included approximately $ 1 million of acquisition- and integration-related costs for professional and services fees related to our acquisition of taqua and approximately $ 3 million of restructuring expense , primarily comprised of approximately $ 2 million related to our 2016 restructuring initiative and approximately $ 1 million related to our taqua restructuring initiative . our 2015 operating expenses included approximately $ 2 million of restructuring expense , comprised of approximately $ 4 million of expense related to our 2015 restructuring initiative , net of approximately $ 2 million of reversals of restructuring expense previously recorded in connection with our 2012 restructuring initiative . we recorded stock-based compensation expense of approximately $ 26 million in 2017 , $ 20 million in 2016 and $ 22 million in 2015. the expense recorded in 2017 includes approximately $ 9 million of incremental expense related to the acceleration of stock options and certain full value stock awards in connection with the merger . see `` results of operations `` in this management 's discussion and analysis of financial condition and results of operations ( `` md & a `` ) for additional discussion of our results of operations for the years ended december 31 , 2017 , 2016 and 2015. restructuring and cost reduction initiatives in connection with the merger , we implemented a restructuring plan in the fourth quarter of 2017 to eliminate certain redundant positions and facilities within the combined companies ( the `` merger restructuring initiative `` ) . accordingly , we recorded $ 8.5 million of restructuring expense in 2017 related to the merger restructuring initiative . we believe that the payments related to the amount accrued at december 31 , 2017 will be completed in 2018. we anticipate that we will record additional future expense in connection with this initiative for headcount and redundant facilities aggregating approximately $ 12 million . we believe that the payments related to this expected additional future expense will be completed by early 2019. we assumed genband 's restructuring liability aggregating approximately $ 4 million at the merger date ( the `` genband restructuring initiative `` ) , primarily related to headcount reductions . we do not expect to record additional expense in connection with this initiative except for adjustments for changes in estimated costs . we expect that the payments related to this assumed liability will be completed in 2018. in connection with the acquisition of taqua , we implemented a restructuring plan in the third quarter of 2016 to eliminate certain redundant positions within the combined companies . on october 24 , 2016 , the audit committee of our board of directors ( the `` audit committee `` ) approved a broader taqua restructuring plan related to headcount and redundant facilities ( collectively , the `` taqua restructuring initiative `` ) . in connection with this initiative , we have recorded approximately $ 2 million of restructuring expense for severance and related costs and estimated costs related to the elimination of redundant facilities , including adjustments recorded for changes in cost estimates for the planned restructuring activities . the actions under the taqua restructuring initiative have been implemented and accordingly , we do not expect to record additional expense in connection with this initiative . the amounts accrued for severance and related costs were fully paid by the end of the third quarter of 2017. we expect that the amounts accrued for facilities costs will be paid by the end of 2018 . 45 on july 25 , 2016 , we announced a program ( the `` 2016 restructuring initiative `` ) to further accelerate our investment in new technologies as the communications industry migrates to a cloud-based architecture and pursues new strategic initiatives , such as new products and an expanded go-to-market footprint in selected geographies and discrete vertical markets . we have recorded an aggregate of approximately $ 2 million of restructuring expense in connection with this initiative , primarily for severance and related costs . the amounts accrued for severance and related costs were fully paid by the end of the third quarter of 2017. we expect that the amounts accrued for facilities will be paid by the end of october 2019. to better align our cost structure to our then-current revenue expectations , in april 2015 , we announced a cost reduction review . on april 16 , 2015 , we initiated a restructuring plan to reduce our workforce by approximately 150 positions , or approximately 13 % of our worldwide workforce ( the `` 2015 restructuring initiative `` ) . we recorded nominal restructuring expense in 2016 and approximately $ 4 million in 2015 in connection with the 2015 restructuring initiative . story_separator_special_tag subsidiaries as of december 31 , 2017 , with the exception of the company 's irish subsidiary , as we do not plan to permanently reinvest these amounts outside the united states . the repatriation of the undistributed earnings would result in withholding taxes imposed on the repatriation . consequently , we have recorded a tax liability of $ 3.2 million , consisting primarily of withholding and distribution taxes , relating to undistributed earnings from these subsidiaries as of december 31 , 2017. had the earnings of the irish subsidiary been determined to not be permanently reinvested outside the u.s. , no additional deferred tax liability would be required due to no withholding taxes or income tax expense being imposed on such repatriation . we assess all material positions taken in any income tax return , including all significant uncertain positions , in all tax years that are still subject to assessment or challenge by relevant taxing authorities . assessing an uncertain tax position begins with the initial determination of the position 's sustainability and is measured at the largest amount of benefit that has a greater than 50 % likelihood of being realized upon ultimate settlement . as of each balance sheet date , unresolved uncertain tax positions must be reassessed , and we will determine whether ( i ) the factors underlying the sustainability assertion have changed and ( ii ) the amount of recognized tax benefit is still appropriate . the recognition and measurement of tax benefits require significant judgment . judgments concerning the recognition and measurement of a tax benefit might change as new information becomes available . on december 22 , 2017 , the u.s. government enacted comprehensive tax legislation commonly referred to as the tax cuts and jobs act ( the `` tax act `` ) . the tax act makes broad and complex changes to the u.s. tax code , including , but not limited to : reducing the u.s. federal corporate tax rate from 35 % to 21 % ; requiring companies to pay a one-time transition tax on certain unrepatriated earnings of foreign subsidiaries ; generally eliminating u.s. federal income taxes on dividends from foreign subsidiaries ; requiring a current inclusion in u.s. federal taxable income of certain earnings ( global intangible low-taxed income ) of controlled foreign corporation ; eliminating the corporate alternative minimum tax ( `` amt `` ) and changing how existing amt credits can be realized ; creating the base erosion anti-abuse tax ; creating a new limitation on deductible interest expense ; changing rules related to uses and limitations of net operating loss carryforwards created in tax years beginning after december 31 , 2017 ; providing a tax deduction for foreign-derived intangible income ; and changing rules related to deductibility of compensation for certain officers . the impact of certain effects of the tax act has been recognized in the period in which the new legislation was enacted per guidance in staff accounting bulletin 118 , which allows for a measurement period to complete the accounting for certain elements of the tax reform . we have not yet completed a full evaluation of the impact of the tax act on our financial statements , however , we have provided a reasonable estimate for the impact related to remeasured deferred tax assets based on the new federal income tax rate of 21 % . we have also provided for the provisional impact related to the tax act 's change to the federal nol and amt carryovers . the total estimated impact of $ 5 million is reflected in income from continuing operations , and increased the tax benefit for the year ended december 31 , 2017. we will continue to make and refine our calculations as 49 additional analysis is completed . we can not predict with certainty how the tax act will affect the company 's financial position or results of operations . results of operations years ended december 31 , 2017 and 2016 revenue . revenue for the years ended december 31 , 2017 and 2016 was as follows ( in millions , except percentages ) : replace_table_token_6_th product revenue is comprised of sales of our network transformation , security and applications solutions . the increase in product revenue in 2017 compared to 2016 was primarily the result of the inclusion genband 's product revenue approximating $ 38 million for the period since the merger date , approximately $ 20 million of higher sales of our security and application products and the inclusion of approximately $ 4 million of 2017 product revenue from taqua . these increases were partially offset by net decreases in sales of certain other products , primarily our legacy gateway products . in 2017 , approximately 24 % of our product revenue was from indirect sales through our channel partner program , compared to approximately 26 % in 2016. in 2017 , approximately 20 % of our product revenue was attributable to sales to enterprise customers , compared to approximately 19 % in 2016. these sales were made through both our direct sales team and indirect sales channel partners . the timing of the completion of customer projects , revenue recognition criteria satisfaction and customer payments may cause our product revenue to fluctuate from one period to the next . service revenue is primarily comprised of hardware and software maintenance and support ( “ maintenance revenue ” ) and network design , installation and other professional services ( “ professional services revenue ” ) . service revenue for the years ended december 31 , 2017 and 2016 was comprised of the following ( in millions , except percentages ) : replace_table_token_7_th our maintenance revenue increased in 2017 compared to 2016 primarily due to the inclusion of approximately $ 21 million of revenue attributable to genband in 2017 for the period since the merger date and the inclusion of approximately $ 5 million of revenue attributable to taqua . the increase in

