Qian中华人民共和国通信行业标准YD/T1522.5—××××会话初始协议（SIP）技术要求第5部分：统一IMS网络的SIP协议TechnicalRequirementsforSessionInitiationProtocolPart5SessionInitiationProtocolBasedontheUnifiedIMS（报批稿）××××-××-××发布××××-××-××实施中华人民共和国工业和信息化部发布YDICS33.040.30M12YD/T1522.5—××××I目次1范围................................................................................12规范性引用文件......................................................................13缩略语..............................................................................14概述................................................................................44.1统一IMS组网......................................................................44.2各接口对SIP协议的要求.............................................................55IMS对SIP消息的扩展要求.............................................................85.1综述...............................................................................85.2Path头字段.........................................................................85.3Service-Route头字段.................................................................85.4Orig参数...........................................................................95.5P-Associated-URI头字段..............................................................95.6P-Called-Party-ID头字段.............................................................105.7P-Visited-Network-ID头字段..........................................................105.8P-Access-Network-Info头字段.........................................................105.9P-Charging-Function-Address头字段....................................................115.10P-Charging-Vector头字段...........................................................125.11鉴权参数.........................................................................135.12安全机制的协商...................................................................145.13前提条件.........................................................................155.14SIP信令压缩......................................................................165.15IMS网络中的SIP定时器...........................................................176SIP协议的应用......................................................................186.1注册和鉴权........................................................................186.2会话管理..........................................................................486.3提供earlymedia的要求.............................................................767其他要求...........................................................................777.1关于IMS路由方式.................................................................777.2DTMF信号传送....................................................................77附录A（资料性附录）提供earlymeadia的信令流程.....................................78A.1Gateway方式......................................................................78A.1.1提供回铃音，支持Precondition流程.................................................78A.1.2提供回铃音，不支持Precondition流程...............................................80A.1.3提供失败音资源，支持Precondition流程.............................................81A.1.4提供失败音资源，不支持Precondition流程.......
