说明：  SIP协议文档简体中文版。会话初始协议（Session Initiation Protocol）是一种信令协议，用于初始、管理和终止网络中的语音和视频会话，具体地说就是用来生成、修改和终结一个或多个参与者之间的会话。
(Simplified Chinese version of the SIP protocol document. Session Initiation Protocol is a signaling protocol used to initiate, manage, and terminate voice and video sessions in a network. Specifically, it is used to generate, modify, and terminate a conversation between one or more participants Conversation.)