REVENUE (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting, Revenue Reconciling Item [Line Items]
Products and solutions net revenues	$ 46,379	$ 47,655	$ 92,789	$ 98,661
Services net revenues	52,236	54,718	103,763	107,819
Total net revenues	98,615	102,373	196,552	206,480
Video products and solutions net revenues [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Products and solutions net revenues	26,927	26,706	58,501	55,527
Audio products and solutions net revenues [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Products and solutions net revenues	19,452	20,949	34,288	43,134
Subscription Arrangement [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Services net revenues	8,326	3,865	16,791	7,586
Nonsoftware Service, Support and Maintenance Arrangement [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Services net revenues	36,076	43,543	69,836	85,429
611710 Educational Support Services [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Services net revenues	7,834	7,310	17,136	14,804
United States [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total net revenues	38,100	45,905	75,648	82,685
Other Americas [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total net revenues	6,364	6,413	12,750	13,204
Europe, Middle East and Africa [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total net revenues	40,206	37,986	80,969	80,121
Asia-Pacific [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total net revenues	$ 13,945	$ 12,069	$ 27,185	$ 30,470