RFC4239: Internet Voice Messaging (IVM)
Network Working Group S. McRae Request for Comments: 4239 IBM Category: Standards Track G. Parsons Nortel Networks ...
RFC4458: Session Initiation Protocol (SIP) URIs for Applications such as Voicemail and Interactive Voice Response (IVR)
Network Working Group C. Jennings Request for Comments: 4458 Cisco Systems Category: Informational F. Audet Nortel Networks ...
RFC4596: Guidelines for Usage of the Session Initiation Protocol (SIP) Caller Preferences Extension
Network Working Group J. Rosenberg Request for Comments: 4596 P. Kyzivat Category: Informational Cisco Systems July 2006 ...
RFC7131: Session Initiation Protocol (SIP) History-Info Header Call Flow Examples
Internet Engineering Task Force (IETF) M. Barnes Request for Comments: 7131 Category: Informational F. Audet ISSN: 2070-1721 Skype ...