Stock-Based Compensation — As of March 31, 2023, we maintained three stock-based incentive compensation plans (“Stock Plans”), as well as an Employee Stock Purchase Plan (“ESPP”). See Note 14, “Stock-Based Compensation and 401(k) Plan,” in our 2022 10-K for further information regarding these plans. The majority of our equity grants are awarded on an annual basis.

For the three-month period ended March 31, 2023, no options to purchase shares of common stock were granted, options to purchase 68,520 shares of common stock were exercised, 1,875 options to purchase shares of common stock were forfeited and no options to purchase shares of common stock expired.

For the three-month period ended March 31, 2023, 1,346,428 Restricted Stock Units (“RSUs”) were granted, 1,013,614 RSUs vested and 40,561 RSUs were forfeited. The fair value of the RSUs granted during the three-month period ended March 31, 2023 was approximately $22.3 million, which will generally be recognized over a period of four years.

For the three-month period ended March 31, 2023, 31,804 deferred stock units were granted and 55,999 vested. The fair value of the deferred stock units granted during the three-month period ended March 31, 2023 was approximately $0.5 million, which was recognized immediately.

For the three-month period ended March 31, 2023, 12,582 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 (in thousands):


	For the Three Months Ended March 31,
	2023		2022
Cost of service revenue	$	343	$	186
Cost of equipment revenue		287		208
Engineering, design and development		754		494
Sales and marketing		738		549
General and administrative		2,919		2,570
Total stock-based compensation expense	$	5,041	$	4,007

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 for both three-month periods ended March 31, 2023 and 2022.