ETSI TS 123 206-2008 数字蜂窝通信系统(第2+阶段).全球移动通信系统(UMTS).电路交换(CS)和IP多媒体子系统(IMS)间的语音呼叫连续性(VCC).第2阶段(版本7.5.0).3GPP TS 23.206(版本7.5.0,第7次发布)
Digital cellular telecommunications system (Phase 2+); Universal Mobile Telecommunications System (UMTS); Voice Call Continuity (VCC) between Circuit Switched (CS) and IP Multimedia Subsystem (IMS); Stage 2