Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Total sales	$ 12,667	$ 11,959	$ 25,416	$ 25,921
Telco | Operating segments
Disaggregation of Revenue [Line Items]
Total sales	8,333	7,287	15,835	14,451
Wireless services sales
Disaggregation of Revenue [Line Items]
Total sales	4,334	4,672	9,581	11,470
Equipment sales: | Telco | Operating segments
Disaggregation of Revenue [Line Items]
Total sales	8,189	6,981	15,464	13,764
Telco repair sales
Disaggregation of Revenue [Line Items]
Total sales	7	8	13	16
Telco recycle sales
Disaggregation of Revenue [Line Items]
Total sales	$ 137	$ 298	$ 358	$ 671