Abstract: SIP is proposed by IETF as IP phone call order protocol which is totally a text modality that to be used to establish, modify and terminate multimedia calls and conversation. This paper introduces SIP and its implementation method, designs the structure of SIP message and transaction layer with class diagram, state diagram, sequence diagram etc. of UML.

Key words: SIP, IP phone, VoIP

摘要： 会话初始化协议(SIP)是IETF提出的IP电话呼叫信令协议，是一个基于文本的协议，用来创建、修改和终止多媒体呼叫与会话。该文介绍了SIP协议及其分层实现方法，采用UML的类图、状态图和序列图等设计了SIP消息包的结构和SIP协议的事务层，并用C++加以具体的实现。

关键词: 会话初始化协议, IP电话, VoIP

CLC Number: 

• TP393