说明：  文中详细介绍了SIP各个层次模块的功能和设计，描述了重要的协议流程 和设计方法，重点阐述了关键技术的使用和实现中需要解决的问题，最后设计了网 络拓扑对协议栈进行了功能测试，测试结果表明该 SIP 协议栈的实现完全满足 VoIP 网关对信令建链功能的需求。
(paper describes in detail the various levels of SIP module and functional design, Description of the important agreements and design process, focuses on the key technology use and realization of the need to address the problem, final design of the network topology of the protocol stack for functional testing, Test results show that the SIP protocol stack to achieve fully meet the VoIP Signaling Gateway to build the demand chain functions.)