REVENUE (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting, Revenue Reconciling Item [Line Items]
Products and solutions net revenues	$ 52,133	$ 54,319	$ 144,922	$ 152,980
Services net revenues	51,913	50,946	155,676	158,765
Total net revenues	104,046	105,265	300,598	311,745
Video products and solutions net revenues [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Products and solutions net revenues	34,124	27,058	92,625	82,585
Audio products and solutions net revenues [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Products and solutions net revenues	18,009	27,261	52,297	70,395
Subscription Arrangement [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Services net revenues	8,786	6,712	25,577	14,298
Nonsoftware Service, Support and Maintenance Arrangement [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Services net revenues	35,033	38,016	104,869	123,445
611710 Educational Support Services [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Services net revenues	8,094	6,218	25,230	21,022
United States [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total net revenues	37,078	38,624	112,726	121,309
Other Americas [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total net revenues	7,466	7,377	20,216	20,581
Europe, Middle East and Africa [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total net revenues	43,179	41,526	124,148	121,647
Asia-Pacific [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Total net revenues	$ 16,323	$ 17,738	$ 43,508	$ 48,208