REVENUE RECOGNITION AND RECEIVABLES - Timing of Revenue Recognition (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation of Revenue [Line Items]
Total revenue	$ 177,979	$ 171,445	$ 523,975	$ 497,906
Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue	169,116	161,312	502,928	469,585
Goods and services transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue	8,863	10,133	21,047	28,321
US Telecom | Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue	81,459	76,542	242,862	221,033
US Telecom | Goods and services transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue	4,111	5,839	9,255	18,140
International Telecom | Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue	87,657	84,770	260,066	248,552
International Telecom | Goods and services transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue	$ 4,752	$ 4,294	$ 11,792	$ 10,181