主要介绍sip协议。sip协议现在是用在voip上最流行的，rfc 3261，完整的描述了sip协议。-Sip protocol introduced. sip protocol voip is now used in the most popular, rfc 3261, a complete descr iption of the sip protocol.

RFC 3261. SIP initiaction protocol details.

rfc 3261的中文版，详细介绍了sip的会话协议，协议格式很详细，非常好-the Chinese version of rfc 3261, details a sip session protocol, the protocol format is very detailed, very good