ETSI TS 123 517-2007 数字蜂窝通信系统(第2+阶段).全球移动通信系统(UMTS).电信和互联网融合业务及高级网络协议(TISPAN).IP多媒体子系统(IMS).功能架构
Digital cellular telecommunications system (Phase 2+); Universal Mobile Telecommunications System (UMTS); Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN); IP Multimedia Subsystem (IMS); Functional architec