SEGMENT REPORTING (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) segment	Jun. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
Segment reporting
Number of reportable segments | segment			3
Revenue
Revenue	$ 123,865	$ 109,098	$ 248,375	$ 220,004
Depreciation and amortization	20,155	21,991	40,662	44,509
Non-cash stock-based compensation	2,175	1,561	3,511	2,721
Operating income (loss)	2,905	7,024	6,254	14,324
Segment Assets
Cash, Cash equivalents, and Investments	94,885		94,885		$ 103,925
Total current assets	199,845		199,845		240,065
Fixed assets, net	526,285		526,285		536,462
Goodwill	60,690		60,690		60,691
Total assets	1,066,574		1,066,574		1,083,711
Total current liabilities	136,572		136,572		147,928
Total debt	87,701		87,701		72,823
Capital Expenditures
Capital expenditures			41,932	31,965
Communication services
Revenue
Revenue	112,964	106,240	223,599	214,145
Mobility
Revenue
Revenue	25,161	21,429	49,842	43,968
Fixed
Revenue
Revenue	65,003	61,504	130,121	124,818
Carrier services
Revenue
Revenue	22,561	22,753	43,180	44,468
Other
Revenue
Revenue	239	554	456	891
Other
Revenue
Revenue	10,901	2,858	24,776	5,859
Renewable Energy
Revenue
Revenue		874	418	2,196
Managed Services
Revenue
Revenue	1,576	1,984	2,726	3,663
Construction
Revenue
Revenue	9,325		21,632
Corporate and Other
Revenue
Depreciation and amortization	1,286	1,656	2,586	3,359
Non-cash stock-based compensation	2,165	1,402	3,442	2,599
Operating income (loss)	(10,411)	(8,799)	(19,009)	(16,623)
Segment Assets
Cash, Cash equivalents, and Investments	15,193		15,193		26,845
Total current assets	17,169		17,169		27,887
Fixed assets, net	10,960		10,960		12,857
Total assets	95,728		95,728		136,035
Total current liabilities	20,113		20,113		22,815
Capital Expenditures
Capital expenditures			1,297	1,519
International Telecom | Operating segments
Revenue
Revenue	86,218	80,064	170,036	162,349
Depreciation and amortization	13,790	14,132	27,616	28,448
Non-cash stock-based compensation	10	28	47	(9)
Operating income (loss)	14,643	14,617	27,786	28,005
Segment Assets
Cash, Cash equivalents, and Investments	48,301		48,301		45,848
Total current assets	108,346		108,346		107,315
Fixed assets, net	447,261		447,261		449,888
Goodwill	25,421		25,421		25,421
Total assets	640,162		640,162		642,834
Total current liabilities	81,709		81,709		80,875
Total debt	71,044		71,044		72,823
Capital Expenditures
Capital expenditures			21,843	19,929
International Telecom | Operating segments | Communication services
Revenue
Revenue	84,642	78,080	167,310	158,686
International Telecom | Operating segments | Mobility
Revenue
Revenue	22,754	19,062	44,575	39,198
International Telecom | Operating segments | Fixed
Revenue
Revenue	59,126	56,567	117,873	115,056
International Telecom | Operating segments | Carrier services
Revenue
Revenue	2,523	1,897	4,406	3,541
International Telecom | Operating segments | Other
Revenue
Revenue	239	554	456	891
International Telecom | Operating segments | Other
Revenue
Revenue	1,576	1,984	2,726	3,663
International Telecom | Operating segments | Managed Services
Revenue
Revenue	1,576	1,984	2,726	3,663
US Telecom | Operating segments
Revenue
Revenue	37,647	28,160	77,921	55,459
Depreciation and amortization	5,079	5,717	10,272	11,602
Operating income (loss)	(556)	1,826	(1,090)	4,019
Segment Assets
Cash, Cash equivalents, and Investments	26,041		26,041		26,921
Total current assets	65,043		65,043		65,806
Fixed assets, net	68,064		68,064		73,717
Goodwill	35,269		35,269		35,270
Total assets	308,514		308,514		265,797
Total current liabilities	33,624		33,624		43,200
Total debt	16,657		16,657
Capital Expenditures
Capital expenditures			18,792	8,883
US Telecom | Operating segments | Communication services
Revenue
Revenue	28,322	28,160	56,289	55,459
US Telecom | Operating segments | Mobility
Revenue
Revenue	2,407	2,367	5,267	4,770
US Telecom | Operating segments | Fixed
Revenue
Revenue	5,877	4,937	12,248	9,762
US Telecom | Operating segments | Carrier services
Revenue
Revenue	20,038	20,856	38,774	40,927
US Telecom | Operating segments | Other
Revenue
Revenue	9,325		21,632
US Telecom | Operating segments | Construction
Revenue
Revenue	9,325		21,632
Renewable Energy | Operating segments
Revenue
Revenue		874	418	2,196
Depreciation and amortization		486	188	1,100
Non-cash stock-based compensation		131	22	131
Operating income (loss)	(771)	(620)	(1,433)	(1,077)
Segment Assets
Cash, Cash equivalents, and Investments	5,350		5,350		4,311
Total current assets	9,287		9,287		39,057
Total assets	22,170		22,170		39,045
Total current liabilities	$ 1,126		1,126		$ 1,038
Capital Expenditures
Capital expenditures				1,634
Renewable Energy | Operating segments | Other
Revenue
Revenue		874	418	2,196
Renewable Energy | Operating segments | Renewable Energy
Revenue
Revenue		$ 874	$ 418	$ 2,196