Stock-Based Compensation — As of September 30, 2022, we maintained three stock-based incentive compensation plans (“Stock Plans”), as well as an Employee Stock Purchase Plan (“ESPP”). See Note 15, “Stock-Based Compensation and 401(k) Plan,” in our 2021 10-K for further information regarding these plans. The majority of our equity grants are awarded on an annual basis.

For the nine-month period ended September 30, 2022, no options to purchase shares of common stock were granted, options to purchase 738,681 shares of common stock were exercised, no options to purchase shares of common stock were forfeited and 30,900 options to purchase shares of common stock expired.

For the nine-month period ended September 30, 2022, 1,349,662 Restricted Stock Units (“RSUs”) were granted, 929,174 RSUs vested and 141,592 RSUs were forfeited. The fair value of the RSUs granted during the nine-month period ended September 30, 2022 was approximately $23.6 million, which will generally be recognized over a period of four years.

For the nine-month period ended September 30, 2022, 90,731 deferred stock units were granted and 156,268 vested. The fair value of the deferred stock units granted during the nine-month period ended September 30, 2022 was approximately $1.4 million, two-thirds of which was recognized immediately and the remainder of which will be recognized over a period of one year.

For the nine-month period ended September 30, 2022, 38,634 shares of common stock were issued under the ESPP.

The following is a summary of our stock-based compensation expense by operating expense line in the Unaudited Condensed Consolidated Statements of Operations, excluding stock-based compensation expense for discontinued operations (in thousands):


	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2022		2021		2022		2021
Cost of service revenue	$	288	$	145	$	752	$	300
Cost of equipment revenue		265		141		733		336
Engineering, design and development		655		379		1,800		866
Sales and marketing		670		601		1,892		1,137
General and administrative		2,812		4,137		8,924		7,505
Total stock-based compensation expense	$	4,690	$	5,403	$	14,101	$	10,144

401(k) Plan — Under our 401(k) plan, all employees who are eligible to participate are entitled to make tax-deferred contributions, subject to Internal Revenue Service limitations. We match 100% of the employee’s first 4% of contributions made, subject to annual limitations. Our matching contributions were $0.5 million and $1.4 million, respectively, during the three- and nine-month periods ended September 30, 2022, and $0.4 million and $1.3 million, respectively, for the prior-year periods.