ETSI ETS 300 729-2000 数字蜂窝通信系统.增强型全速率(EFR)语音业务流信道非连续传输(DTX).GSM 06.81(第2版,版本5.2.1,1996年发布)
Digital Cellular Telecommunications System; Discontinuous Trasmission (DTX) for Enhanced Full rate (EFR) Speech Traffic Channels Second Edition; GSM 06.81 Version 5.2.1 Release 1996