ETSI PRETS 300 516-1995 欧洲数字蜂窝通信系统(第2阶段).呼叫等待(CW)及呼叫保持(HOLD)补充业务.第1阶段.GSM 02.83(第2版,版本4.6.7)
European Digital Cellular Telecommunications System (Phase 2); Call Waiting (CW) and Call Holding (HOLD) Supplementary Services - Stage 1 (GSM 02.83 Version 4.6.7) Second Edition