ETSI TS 123 091-2000 数字蜂窝通信系统(第2+阶段)(GSM).全球移动通信系统(UMTS).显式呼叫转移(ECT)补充业务-第2阶段.3G TS 23.091(版本3.1.0,1999年发布)
Digital Cellular Telecommunications System (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS); Explicit Call Transfer (ECT) Supplementary Service - Stage 2 3G TS 23.091 Version 3.1.0 Release 1999