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)。

youdao

When I see people drink the water, I can't even describe the feeling -- it's as if I'm experiencing the first sip all over again.

CNN: From 58 pounds to thriving