https://app.knowbase.one/vault/rfc/docid/6362
RFC5850: A Call Control and Multi-Party Usage Framework for the Session Initiation Protocol (SIP)
Internet Engineering Task Force (IETF) R. Mahy Request for Comments: 5850 Unaffiliated Category: Informational R. Sparks ISSN: 2070-1721 Tekelec ...