UNAUDITED QUARTERLY RESULTS - Summary of unaudited quarterly data (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 69,748	$ 68,129	$ 68,687	$ 67,028	$ 62,800	$ 62,014	$ 60,410	$ 59,404	$ 273,592	$ 244,628	$ 244,164
Direct costs of network, sales and services, exclusive of depreciation and amortization	33,585	33,573	32,641	31,154	29,924	30,787	30,569	29,030	130,954	120,310	127,423
Direct costs of customer support	6,556	6,898	6,481	6,728	5,387	5,407	5,374	5,110	26,664	21,278	19,861
Amortization of acquired technologies	1,179	1,179	1,179	1,179	875	875	875	875	4,718	3,500	3,811
Exit activities, restructuring and impairments	610	124	645	43	1,217	123	1,304	189	1,422	2,833	1,411
Net income (loss)	$ 21	$ (2,450)	$ (1,997)	$ 107	$ 4,198	$ (1,788)	$ (2,612)	$ (1,500)	$ (4,318)	$ (1,702)	$ (3,622)
Basic and diluted net loss per share (in dollars per share)	$ 0.00	$ (0.05)	$ (0.04)	$ 0.00	$ 0.08	$ (0.04)	$ (0.05)	$ (0.03)	$ (0.09)	$ (0.03)	$ (0.07)