说明: 一份详细的SIP协议的数据流分析的文档,该文档有两百多页,包含的SIP消息的各种情况,内容实用,可供SIP协议的VoIP开发者做一份详细的SIP数据流的分析手册。 (a detailed SIP protocol data flow analysis of the document, the document is over 200 pages and contains information of the various SIP, as practical, the SIP for VoIP developers to do a detailed SIP data flow analysis handbook.)