This paper firstly introduces the definition, operation type, instruction and voice communication protocol including H.323 of ITU-T and Session Initiation Protocol (SIP) of IETF.

• 本文首先介绍了IP电话的定义、业务类型、结构以及语音通信协议ITU-T的H.；323系列和IETF的会话初始化协议(SIP)。