Revenue, Deferred Revenue And Prepaid Commissions - Additional Information and Disaggregation of Revenue (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) revenue_component	Jun. 30, 2019 USD ($)
Revenues from External Customers and Long-Lived Assets
Total revenue	$ 35,739	$ 39,525	$ 73,006	$ 81,288
Deferred revenue recognized from previous period			20,200
Remaining performance obligation	48,400		48,400
United States
Revenues from External Customers and Long-Lived Assets
Total revenue	35,328	38,447	71,831	78,213
International
Revenues from External Customers and Long-Lived Assets
Total revenue	411	1,078	1,175	3,075
Wireless products and services
Revenues from External Customers and Long-Lived Assets
Total revenue	21,078	22,127	42,465	44,737
License
Revenues from External Customers and Long-Lived Assets
Total revenue	749	1,676	1,704	4,516
Services
Revenues from External Customers and Long-Lived Assets
Total revenue	3,812	4,835	8,359	10,040
Hardware
Revenues from External Customers and Long-Lived Assets
Total revenue	601	842	$ 1,327	1,805
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	$ 9,499	$ 10,045	$ 19,151	$ 20,190
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