2J.Rosenberg, H.SchulzrinneIEF-RFC-3262 (Reliability of Provisional Responses in the Session Initiation Protocol).http://www.ietf. org/rfc/rfc3262.txt?number=3262.
3G.Camarillo,白建军,彭晖,田敏等译.SIP揭密.人民邮电出版社,2003
4SIP:Understanding the Session Initiation Protocol.Second Edition,2004