Condensed Consolidating Financial Information - Condensed Consolidating Statement of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Cash flows provided by operating activities:	$ 2,603	$ 2,521
Cash flows from investing activities:
Second-generation network costs (including interest)	(1,598)	(4,018)
Property and equipment additions	(2,949)	(1,133)
Purchase of intangible assets	(361)	(657)
Net cash used in investing activities	(4,908)	(5,808)
Cash flows provided by financing activities:
Proceeds from issuance of stock to Terrapin	6,500	10,000
Proceeds from issuance of common stock and exercise of options and warrants	28	61
Net cash provided by financing activities	6,528	10,061
Effect of exchange rate changes on cash	160	(240)
Net increase in cash and cash equivalents	4,383	6,534
Cash and cash equivalents, beginning of period	7,476	7,121
Cash and cash equivalents, end of period	11,859	13,655
Reportable Legal Entities | Parent Company
Condensed Financial Statements, Captions [Line Items]
Cash flows provided by operating activities:	1,175	1,401
Cash flows from investing activities:
Second-generation network costs (including interest)	(1,560)	(4,018)
Property and equipment additions	(1,732)	(747)
Purchase of intangible assets	(361)	(657)
Net cash used in investing activities	(3,653)	(5,422)
Cash flows provided by financing activities:
Proceeds from issuance of stock to Terrapin	6,500	10,000
Proceeds from issuance of common stock and exercise of options and warrants	28	61
Net cash provided by financing activities	6,528	10,061
Effect of exchange rate changes on cash	0	0
Net increase in cash and cash equivalents	4,050	6,040
Cash and cash equivalents, beginning of period	3,530	3,166
Cash and cash equivalents, end of period	7,580	9,206
Reportable Legal Entities | Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Cash flows provided by operating activities:	1,218	673
Cash flows from investing activities:
Second-generation network costs (including interest)	0	0
Property and equipment additions	(1,136)	(259)
Purchase of intangible assets	0	0
Net cash used in investing activities	(1,136)	(259)
Cash flows provided by financing activities:
Proceeds from issuance of stock to Terrapin	0	0
Proceeds from issuance of common stock and exercise of options and warrants	0	0
Net cash provided by financing activities	0	0
Effect of exchange rate changes on cash	0	0
Net increase in cash and cash equivalents	82	414
Cash and cash equivalents, beginning of period	719	672
Cash and cash equivalents, end of period	801	1,086
Reportable Legal Entities | Non- Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Cash flows provided by operating activities:	210	447
Cash flows from investing activities:
Second-generation network costs (including interest)	(38)	0
Property and equipment additions	(81)	(127)
Purchase of intangible assets	0	0
Net cash used in investing activities	(119)	(127)
Cash flows provided by financing activities:
Proceeds from issuance of stock to Terrapin	0	0
Proceeds from issuance of common stock and exercise of options and warrants	0	0
Net cash provided by financing activities	0	0
Effect of exchange rate changes on cash	160	(240)
Net increase in cash and cash equivalents	251	80
Cash and cash equivalents, beginning of period	3,227	3,283
Cash and cash equivalents, end of period	3,478	3,363
Eliminations
Condensed Financial Statements, Captions [Line Items]
Cash flows provided by operating activities:	0	0
Cash flows from investing activities:
Second-generation network costs (including interest)	0	0
Property and equipment additions	0	0
Purchase of intangible assets	0	0
Net cash used in investing activities	0	0
Cash flows provided by financing activities:
Proceeds from issuance of stock to Terrapin	0	0
Proceeds from issuance of common stock and exercise of options and warrants	0	0
Net cash provided by financing activities	0	0
Effect of exchange rate changes on cash	0	0
Net increase in cash and cash equivalents	0	0
Cash and cash equivalents, beginning of period	0	0
Cash and cash equivalents, end of period	$ 0	$ 0