STOCK-BASED COMPENSATION PLANS

2019 Stock Incentive Plan

At the Company's annual meeting of stockholders held on June 5, 2019, the Company's stockholders approved the Ribbon Communications Inc. Incentive Award Plan (the "2019 Plan"). The 2019 Plan had previously been approved by the Board, subject to stockholder approval. Under the 2019 Plan, the Company may grant awards up to 7.0 million shares of common stock (subject to adjustment in the event of stock splits and other similar events), plus 5.1 million shares of common stock that remained available for issuance under the Company's Amended and Restated Stock Incentive Plan (the "2007 Plan") on June 5, 2019, plus any shares covered by awards under the 2007 Plan (or the Company's other prior equity compensation plans) that again become available for grant pursuant to the provisions of the 2007 Plan. The 2019 Plan provides for the grant of options to purchase the Company's common stock ("stock options"), stock appreciation rights ("SARs"), restricted stock awards ("RSAs"), performance-based stock awards ("PSAs"), restricted stock units ("RSUs"), performance-based stock units ("PSUs") and other stock- or cash-based awards. Awards can be granted under the 2019 Plan to the Company's employees, officers and non-employee directors, as well as consultants and advisors of the Company and its subsidiaries. At December 31, 2019, there were 7.1 million shares available for future issuance under the 2019 Plan.

2007 Plan

The Company's 2007 Plan provides for the award of stock options, SARs, RSAs, RSUs, PSAs, PSUs and other stock-based awards to employees, officers, non-employee directors, consultants and advisors of the Company and its subsidiaries. On and following June 5, 2019, with the exception of shares underlying awards outstanding as of that date, no additional shares may be granted under the 2007 Plan.

2002 Stock Option Plan

In connection with the Edgewater Acquisition, the Company assumed Edgewater's Amended and Restated 2002 Stock Option Plan (the "Edgewater Plan") for all outstanding options as of the Edgewater Acquisition Date (the "Edgewater Options"). The Edgewater Options were converted to Ribbon stock options (the "Ribbon Replacement Options") using a conversion factor of 0.17, which was calculated based on the acquisition consideration of $1.20 per share of Edgewater common stock divided by the weighted average of the closing price of Ribbon common stock for the ten consecutive days ending with the trading day that preceded the Edgewater Acquisition Date. This conversion factor was also used to convert the exercise prices of the Edgewater Options to Ribbon Replacement Option exercise prices. The Ribbon Replacement Options are vesting under the same schedules as the respective Edgewater Options.

The fair values of the Edgewater Options assumed were estimated using a Black-Scholes option pricing model. The Company recorded $0.7 million as additional purchase consideration for the fair value of the Edgewater Options. The fair value of the Ribbon Replacement Options attributable to future service totaled $1.0 million, which is being recognized over a weighted average period of approximately two years.

2012 Stock Incentive Plan

In connection with the acquisition of Performance Technologies, Inc. ("PT"), the Company assumed PT's 2012 Amended Performance Technologies, Incorporated Omnibus Incentive Plan, and subsequently renamed it the 2012 Stock Incentive Plan (the "2012 Plan"). In December 2014, all of the unissued shares under the 2012 Plan were transferred to the 2007 Plan. Any outstanding awards under the 2012 Plan that in the future expire, terminate, are canceled, surrendered or forfeited, or are repurchased by the Company will be returned to the 2019 Plan. Accordingly, at December 31, 2019 there were no shares available for future issuance under the 2012 Plan.

2008 Stock Incentive Plan

In connection with the acquisition of Network Equipment Technologies, Inc. ("NET"), the Company assumed NET's 2008 Equity Incentive Plan and subsequently renamed it the 2008 Stock Incentive Plan (the "2008 Plan"). In December 2014, all of the unissued shares under the 2008 Plan were transferred to the 2007 Plan. Any outstanding awards under the 2008 Plan that in the future expire, terminate, are canceled, surrendered or forfeited, or are repurchased by the Company will be returned to the 2019 Plan. Accordingly, at December 31, 2019 there were no shares available for future issuance under the 2008 Plan.

Treatment of Equity Awards in Connection with the Merger

In connection with the Merger, the Company accelerated the vesting of all then-outstanding stock options and certain then-outstanding full value awards on the Merger Date. In addition, the vesting schedules of certain remaining unvested full value awards were adjusted. Such vesting and adjustments are described below:

Stock options - each stock option outstanding as of five business days prior to the Merger Date became vested in full as of that date (to the extent not previously vested), and the holders of such stock options were permitted to exercise their stock options from October 20, 2017 through October 24, 2017, after which date all remaining stock options, with certain exceptions, were canceled. The Company accelerated the vesting of 0.3 million stock options and subsequently canceled 4.5 million vested unexercised stock options in connection with this transaction. Any stock options granted under the 2008 Plan and 2012 Plan were not canceled, as these plans do not permit such cancellations. These stock options continue to be outstanding until they are either exercised or expire.

RSAs and RSUs - as prescribed by the Company's 2007 Plan, any unvested RSAs and RSUs that were scheduled to vest within one year from the Merger Date vested in full as of the Merger Date. The vesting schedules of the remaining unvested RSAs and RSUs were then accelerated by one year. Certain executives had specific terms and conditions related to their RSAs detailed in their employment agreements or amendments thereto (the "employment terms"). The accelerated vesting of and future vesting schedule adjustments to the RSAs held by these individuals were completed in accordance with their individual employment terms. In accordance with the terms of their RSA grants, unvested RSAs held by the then-current members of the Board were accelerated on a pro rata basis based on the amount of time the unvested RSAs were outstanding compared to the originally scheduled vesting date. Unvested PSUs granted to the Company's then-current President and Chief Executive Officer, who separated from the Company effective December 13, 2017 (the "Former CEO"), were converted to RSAs in accordance with his employment terms; certain of those converted grants were accelerated, and the remaining RSAs continued to vest according to their terms, but with the elimination of any required satisfaction of the performance metrics associated with the awards when they were originally granted as PSUs. In total, the Company accelerated the vesting of and released 1.1 million RSAs and approximately 36,000 RSUs in connection with the Merger.

PSUs - any unvested PSUs were accelerated in accordance with the employment agreement of each individual PSU holder. The remaining unvested units would continue to vest according to their terms, with the exception of the PSU grants held by the Former CEO, as discussed above. The Company accelerated the vesting of and released approximately 98,000 PSUs in connection with the Merger.

Executive Equity Arrangements

Stock-for-Cash Bonus Election

In connection with the Company’s annual incentive program, certain executives of the Company were given the choice to receive a portion, ranging from 10% to 50% (the "Elected Percentage") of their fiscal year 2018 bonuses (the “2018 Bonus”), if any were earned, in the form of shares of the Company’s common stock (the “2018 Bonus Shares” and such program, the “Stock Bonus Election Program”). Each executive could also elect not to participate in this program and to earn his or her 2018 Bonus, if any, in the form of cash. Any executive who elected to receive a portion of his or her 2018 Bonus in stock would also receive an uplift of 20% of the value of the 2018 Bonus Shares in additional shares of the Company’s common stock (the “Uplift Shares”) with the exception of the Company’s Chief Executive Officer and his senior leadership team. Under the Stock Bonus Election Program, the amount of the 2018 Bonus, if any, for each executive was determined by the Compensation Committee of the Board (the "Compensation Committee").

The number of shares earned by each of the 23 participants in the Stock Bonus Election Program was calculated by multiplying each participant's 2018 Bonus by the applicable Elected Percentage (plus the amount attributable to Uplift Shares, if applicable) and dividing the resulting amount by $4.97, the closing price of the Company’s common stock on March 8, 2019, the date of the company-wide cash bonus payments. The Company granted 198,949 shares in the aggregate in connection with the 2018 Bonus Shares on March 15, 2019, and such shares were fully vested on the date of grant. However, notwithstanding that each such share of common stock was fully vested, each participant in the Stock Bonus Election Program was contractually restricted from trading the 2018 Bonus Shares for five months after the date of grant. Both the grant and vesting of the 2018 Bonus Shares are included in the RSU table below.

The Company determined that the grant date criteria for the 2018 Bonus Shares and Uplift Shares had not been met as of December 31, 2018, as the number of shares to be granted to each executive had not been determined. The Company recorded stock-based compensation expense totaling $1.1 million in connection with the Stock Bonus Program in 2018 and recorded a liability in connection with the future issuance of the 2018 Bonus Shares and Uplift Shares. This liability was reclassified to equity at the time the shares were granted.

Performance-Based Stock Grants

In addition to granting RSAs and RSUs to its executives and certain of its employees, the Company also grants PSUs to certain of its executives.

2019 PSU Grants. In March and April 2019, the Company granted certain of its executives an aggregate of 872,073 PSUs, of which 523,244 PSUs had both performance and service conditions (the "Performance PSUs") and 348,829 PSUs had both market and service conditions (the "Market PSUs").

Each executive's Performance PSU grant is comprised of three consecutive fiscal year performance periods from 2019 through 2021 (each, a "Fiscal Year Performance Period"), with one-third of the Performance PSUs attributable to each Fiscal Year Performance Period. The number of shares that will vest for each Fiscal Year Performance Period will be based on the achievement of certain metrics related to the Company's financial performance for the applicable year on a standalone basis (each, a "Fiscal Year Performance Condition"). In the third quarter of 2019, the Company adjusted the 2019 Performance PSU goals to reflect the changes to the Company's calculation of certain metrics. There was no incremental expense in connection with this modification. The Company's achievement of the 2019 Fiscal Year Performance Conditions (and the number of shares of Company common stock to vest as a result thereof) will be measured on a linear sliding scale in relation to specific threshold, target and stretch performance conditions. The Company is recording stock-based compensation expense for the Performance PSUs based on its assessment of the probability that each performance condition will be achieved and the level, if any, of such achievement. As of December 31, 2019, the Company determined that the grant date criteria for the 2020 and 2021 Fiscal Year Performance Periods had not been met, as the 2020 and 2021 Fiscal Year Performance Conditions had not been established by the Company. Accordingly, the stock-based compensation expense recorded in the year ended December 31, 2019 in connection with the Performance PSUs is related only to those PSUs with 2019 Fiscal Year Performance Conditions. The Compensation Committee will determine the number of shares earned, if any, after the Company's financial results for each Fiscal Year Performance Period are finalized. Upon the determination by the Compensation Committee of the number of shares that will be received upon vesting of the Performance PSUs, such number of shares will become fixed and the unamortized expense will be recorded through the remainder of the service period that ends on March 15, 2022, at which time the total Performance PSUs earned, if any, will vest, pending each executive's continued employment with the Company through that date. The number of shares of common stock to be achieved upon vesting of the Performance PSUs will in no event exceed 200% of the Performance PSUs. Shares subject to the Performance PSUs that fail to be earned will be forfeited.

The Market PSUs have one three-year performance period, which will end on December 31, 2021 (the "Market Performance Period"). The number of shares subject to the Market PSUs that will vest, if any, on March 15, 2022, will be dependent upon the Company's total shareholder return ("TSR") compared with the TSR of the companies included in the Nasdaq Telecommunications Index for the same Market Performance Period, measured by the Compensation Committee after the Market Performance Period ends. The shares determined to be earned will vest on March 15, 2022, pending each executive's continued employment with the Company through that date. The number of shares of common stock to be achieved upon vesting of the Market PSUs will in no event exceed 200% of the Market PSUs. Shares subject to the Market PSUs that fail to be earned will be forfeited.

2018 PSU Grant. In May 2018, the Company granted its then-current President and Chief Executive Officer, Mr. Hobbs, 195,000 PSUs with both performance and service conditions (the “2018 PSUs”). Of the 195,000 2018 PSUs, one-half each would vest based on the achievement of two separate metrics related to the Company’s 2018 financial performance (the “2018 Performance Conditions”). The Company’s achievement of the 2018 Performance Conditions (and the shares of Company common stock to vest as a result thereof) were measured on a linear sliding scale in relation to specific threshold, target and stretch performance conditions. The number of shares of common stock to be received upon vesting of the 2018 PSUs would in no event exceed 150% of the 2018 PSUs. In the year ended December 31, 2018, the Company recorded stock-based compensation expense for the 2018 PSUs based on its assessment of the probability that each performance condition would be achieved and the level, if any, of such achievement. The Company recorded $0.3 million of stock-based compensation expense in the year ended December 31, 2018 in connection with the 2018 PSUs. In February 2019, the Compensation Committee determined that the performance metrics for one-half of the 2018 PSUs had been achieved at the 106.49% achievement level and one-half of the 2018 PSUs had been achieved at the 150% level, for a total of 250,075 shares earned. However, in April 2019, the Compensation Committee subsequently determined that the performance metrics for the entire 2018 PSUs had been achieved at the 150% level, for a total of 292,500 shares eligible to be issued (the "2018 Shares Earned"), pending Mr. Hobbs' continued employment with the Company through December 31, 2020. In connection with Mr. Hobbs' separation from the Company effective December 31, 2019, the vesting schedule for the 2018 Shares Earned was accelerated and the shares were released on January 30, 2020 (see "Accelerated Vesting of Unvested Stock Units Held by Mr. Hobbs" below).

2017 PSU Grants. On March 31, 2017, the Company granted an aggregate of 165,000 PSUs with both market and service conditions to five of its executives (the "2017 PSUs"). The terms of each PSU grant were such that up to one-third of the shares subject to the respective PSU grant would vest, if at all, on each of the respective first, second and third anniversaries of the date of grant, depending on the Company's TSR compared with the TSR of the companies included in the Nasdaq Telecommunications Index for the same fiscal year, measured by the Compensation Committee after each of the fiscal years as defined by each grant (each, a "Performance Period"). The shares determined to be earned would vest on the anniversary of the grant date following each Performance Period. Shares subject to the PSUs that failed to be earned would be forfeited. In March 2018, the Compensation Committee determined that the performance metrics for the 2017 PSUs for the 2017 Performance Period had been achieved at the 130% level and accordingly, 33,584 shares in the aggregate were released to the three remaining executives holding such outstanding grants, comprised of 25,834 shares, representing the 100% achievement of target, granted on March 31, 2017, and 7,750 shares, representing the 30% achievement over target, granted on March 31, 2018. In February 2019, the Compensation Committee determined that the performance metrics for the 2017 PSUs for the 2018 Performance Period had been achieved at the 61.4% level and accordingly, 9,464 shares were released to the three remaining executives holding such outstanding grants on March 31, 2019. The shares that failed to be earned for the 2018 Performance Period, aggregating 5,950 shares, were forfeited. Accordingly, at December 31, 2019, there were no remaining unvested 2017 PSUs outstanding. The release and forfeiture of the shares related to the 2018 Performance Period are included in the PSU table below.

PSUs that include a market condition require the use of a Monte Carlo simulation approach to model future stock price movements based upon the risk-free rate of return, the volatility of each entity and the pair-wise covariance between each entity. These results are then used to calculate the grant date fair values of the respective PSUs. The Company is required to record expense for the PSUs with market conditions through their respective final vesting dates regardless of the number of shares that are ultimately earned.

Accelerated Vesting of Unvested Stock Units Held by Mr. Hobbs. On November 13, 2019, the Company announced that, effective that date, Mr. Hobbs was no longer serving as the President and Chief Executive Officer of Ribbon, and, also on and effective November 13, 2019, the Board appointed Steven Bruny, the Company's Executive Vice President, Global Sales & Services, and Kevin Riley, the Company's Executive Vice President, Advanced R&D and Chief Technology Officer, as Interim Co-Presidents and Chief Executive Officers, to assume the duties of the Company's President and Chief Executive Officer while the Board searched for a permanent successor to Mr. Hobbs. Mr. Hobbs resigned his position as a member of the Board effective December 27, 2019 and separated from the Company effective December 31, 2019. In connection with his separation from the Company and in accordance with the terms of his employment agreement with the Company, the vesting of certain of Mr. Hobbs' RSUs and PSUs were accelerated, some of which were released on January 30, 2020, with certain other PSUs, if any are earned, scheduled for release no later than December 15, 2020.

Stock Options

Stock options granted under the 2019 Plan expire ten years from the date of grant. Outstanding stock options granted under the Edgewater Plan expire ten years from the date of grant. Outstanding stock options granted under the 2008 Plan expire either seven or ten years from the date of grant. Outstanding stock options granted under the 2012 Plan expire ten years from the date of grant. There were no stock options outstanding under either the 2019 Plan or the 2007 Plan at December 31, 2019. The grant date fair value of stock options, adjusted for estimated forfeitures, is recognized as expense on a straight-line basis over the requisite service period, which is generally the vesting period. Forfeitures are estimated based on historical experience.

The activity related to the Company's outstanding stock options during the year ended December 31, 2019 was as follows:



	Number of Shares		Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (years)	Aggregate Intrinsic Value (in thousands)
Outstanding at January 1, 2019	582,061		$	9.01
Granted	—		$	—
Exercised	(127,334	)	$	1.85
Forfeited	(38,666	)	$	2.55
Expired	(118,937	)	$	12.43
Outstanding at December 31, 2019	297,124		$	11.55	4.95	$	122
Vested or expected to vest at December 31, 2019	293,782		$	11.65	4.92	$	119
Exercisable at December 31, 2019	260,152		$	12.89	4.59	$	85

The Company did not grant stock options during the years ended December 31, 2019 and 2018. The grant date fair values of stock options granted in the year ended December 31, 2017 were estimated using the Black-Scholes valuation model with the following assumptions:



Risk-free interest rate		1.22% - 1.95%
Expected dividends		—
Weighted average volatility		51.1%
Expected life (years)		5.0

The risk-free interest rate used is the average U.S. Treasury Constant Maturities Rate for the expected life of the award. The expected dividend yield of zero is based on the fact that the Company has never paid dividends and has no present intention to pay cash dividends. The expected life for stock options is based on a combination of the Company's historical option patterns and expectations of future employee actions.

The weighted average grant-date fair value of options granted for the year ended December 31, 2017 was $3.05.

The total intrinsic values of options exercised were $0.5 million for the year ended December 31, 2019, approximately $39,000 for the year ended December 31, 2018 and $0.2 million for the year ended December 31, 2017.

The Company received cash from option exercises of $0.2 million in the year ended December 31, 2019, $0.1 million in the year ended December 31, 2018 and $0.6 million in the year ended December 31, 2017.

Restricted Stock Grants - Restricted Stock Awards and Restricted Stock Units

The Company's outstanding restricted stock grants consist of both RSAs and RSUs. Holders of unvested RSAs have voting rights and rights to receive dividends, if declared; however, these rights are forfeited if the underlying unvested RSA shares are forfeited. Holders of unvested RSUs do not have such voting and dividend rights. The grant date fair value of restricted stock grants, adjusted for estimated forfeitures, is recognized as expense on a straight-line basis over the requisite service period. The fair value of restricted stock grants is determined based on the market value of the Company's shares on the date of grant.

The activity related to the Company's RSAs for the year ended December 31, 2019 was as follows:



	Shares		Weighted Average Grant Date Fair Value
Unvested balance at January 1, 2019	1,508,011		$	6.90
Granted	—		$	—
Vested	(967,291	)	$	6.90
Forfeited	(52,744	)	$	7.04
Unvested balance at December 31, 2019	487,976		$	6.87

The activity related to the Company's RSUs for the year ended December 31, 2019 was as follows:



	Shares		Weighted Average Grant Date Fair Value
Unvested balance at January 1, 2019	636,300		$	6.52
Granted	2,828,832		$	4.98
Vested	(537,416	)	$	6.04
Forfeited	(137,656	)	$	5.35
Unvested balance at December 31, 2019	2,790,060		$	5.11

The total grant date fair value of vested restricted stock grant shares was $9.9 million in the year ended December 31, 2019, $9.7 million in the year ended December 31, 2018 and $19.1 million in the year ended December 31, 2017.

Performance-Based Stock Units

Holders of unvested PSUs do not have voting and dividend rights. The Company recognizes stock-based compensation expense for PSUs without market conditions on a straight-line basis, with the amount recorded based upon the expected level of achievement as of each period-end, recording cumulative adjustments in the period when the expected level of achievement changes. The Company recognizes the grant date fair value of PSUs on a graded attribution basis through the vest date of the respective awards so long as it remains probable that the related service conditions will be satisfied.

The activity related to the Company's PSUs for the year ended December 31, 2019 was as follows:



	Shares		Weighted Average Grant Date Fair Value
Unvested balance at January 1, 2019	210,416		$	5.77
Granted	872,073		$	6.03
Vested	(9,466	)	$	8.55
Forfeited	(5,950	)	$	8.55
Unvested balance at December 31, 2019	1,067,073		$	5.94

The total grant date fair value of vested performance-based stock grant shares was $0.1 million in the year ended December 31, 2019, $0.6 million in the year ended December 31, 2018 and $1.4 million in the year ended December 31, 2017.

ESPP

The ESPP is designed to provide eligible employees of the Company and its participating subsidiaries an opportunity to purchase common stock of the Company through accumulated payroll deductions.

The ESPP provides for six-month consecutive offering periods, with the purchase price of the stock equal to 85% of the lesser of the market price on the first or last day of the offering period. The maximum number of shares of common stock an employee may purchase during each offering period is 500, subject to certain adjustments pursuant to the ESPP.

In May 2017, the Compensation Committee determined to suspend all offering periods under the ESPP, effective September 1, 2017, until such time after the Merger Date as the Compensation Committee determined was best in its sole discretion. The Company's Board voted to re-implement the ESPP effective December 1, 2018 for employees in certain geographic regions, with the first purchase date of the re-implemented ESPP completed on May 31, 2019.

At December 31, 2019, 5.0 million shares, the maximum number of shares that may be issued under the ESPP, were authorized and 1.1 million shares were available under the ESPP for future issuance. The ESPP will expire on May 20, 2020.

Stock-Based Compensation

The consolidated statements of operations included stock-based compensation for the years ended December 31, 2019, 2018 and 2017 as follows (in thousands):



	Year ended December 31,
	2019		2018		2017
Product cost of revenue	$	76	$	114	$	514
Service cost of revenue	478		345		1,448
Research and development	1,898		1,797		7,337
Sales and marketing	3,028		2,935		4,885
General and administrative	7,121		5,881		11,473
	$	12,601	$	11,072	$	25,657

There was no income tax benefit for employee stock-based compensation expense for the years ended December 31, 2019, 2018 and 2017 due to the valuation allowance recorded.

Stock-based compensation expense recorded for the year ended December 31, 2019 included $1.6 million of incremental expense related to the accelerated vesting of RSUs and PSUs held by the former President and Chief Executive Officer in connection with his separation from the Company effective December 31, 2019. Stock-based compensation expense recorded for the year ended December 31, 2017 included $8.6 million of incremental expense related to the acceleration of stock options and full value awards and subsequent adjustments to the vesting schedules of the remaining unvested full value awards in connection with the Merger. In addition, the Company recorded $1.6 million of incremental expense related to the accelerated vesting of RSAs held by a former President and Chief Executive Officer in connection with his separation from the Company effective December 13, 2017.

At December 31, 2019, there was $11.3 million, net of expected forfeitures, of unrecognized stock-based compensation expense related to unvested stock options, RSAs, RSUs and PSUs. This expense is expected to be recognized over a weighted average period of approximately two years.

Common Stock Reserved

Common stock reserved for future issuance at December 31, 2019 consists of the following:



2019 Plan	7,051,559
ESPP	1,148,867
	8,200,426

The Company's policy is to issue authorized but unissued shares upon the exercise of stock options, to grant restricted common stock, to settle restricted stock units and performance-based stock units, and to authorize the purchase of shares of the Company's common stock under the ESPP.