Revenue, Deferred Revenue And Prepaid Commissions - Additional Information and Disaggregation of Revenue (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) revenue_component	Sep. 30, 2019 USD ($)
Revenues from External Customers and Long-Lived Assets
Total revenue	$ 37,693	$ 39,453	$ 110,699	$ 120,741
Deferred revenue recognized from previous period			25,000
Remaining performance obligation	51,700		51,700
United States
Revenues from External Customers and Long-Lived Assets
Total revenue	36,819	38,312	108,650	116,525
International
Revenues from External Customers and Long-Lived Assets
Total revenue	874	1,141	2,049	4,216
Wireless products and services
Revenues from External Customers and Long-Lived Assets
Total revenue	20,828	21,814	63,293	66,552
License
Revenues from External Customers and Long-Lived Assets
Total revenue	1,988	2,723	3,692	7,239
Services
Revenues from External Customers and Long-Lived Assets
Total revenue	4,772	4,202	13,132	14,242
Hardware
Revenues from External Customers and Long-Lived Assets
Total revenue	554	689	1,880	2,493
Subscription
Revenues from External Customers and Long-Lived Assets
Total revenue	24	0	$ 24	0
Maintenance
Revenues from External Customers and Long-Lived Assets
Typical duration of revenue recognition			Maintenance revenue is for ongoing support of our software solutions or related equipment and access to when-and-if available software updates.
Total revenue	$ 9,527	$ 10,025	$ 28,678	$ 30,215
Wireless
Revenues from External Customers and Long-Lived Assets
Revenue primary component | revenue_component			2
Software
Revenues from External Customers and Long-Lived Assets
Revenue primary component | revenue_component			2