oSIP实现了会话初始协议Session Initiation (由IETF发布为RFC 3261)。它可以为多媒体应用程序(IP电话，等等)提供信令功能。它为SIP语法提供了一个完全可用的语法分析器，实现了草案中定义的“事务”层。它也提供了一个SDP分析器和为用户代理提供的额外功能。它可以用于建造代理服务器和IP电话-oSIP achieve Session Initiation Protocol Session Initiation (released by the IETF as RFC 3261). It can for multimedia applications (IP phone, etc.) signaling functions. It SIP Grammar providing a complete syntax analyzer can be used to achieve a draft definition of "services" layer. It also provided an SDP analyzer for the user agent and provide the additional functionality. It can be used in the construction of the proxy server and IP Telephony