https://app.knowbase.one/vault/rfc/docid/6996
RFC6432: Carrying Q.850 Codes in Reason Header Fields in SIP (Session Initiation Protocol) Responses
Internet Engineering Task Force (IETF) R. Jesske Request for Comments: 6432 L. Liess Category: Standards Track Deutsche Telekom ISSN: 2070-1721 November 2011 ...
https://app.knowbase.one/vault/rfc/docid/9324
RFC8606: ISDN User Part (ISUP) Cause Location Parameter for the SIP Reason Header Field
Internet Engineering Task Force (IETF) R. Jesske Request for Comments: 8606 Deutsche Telekom Updates: 3326 June 2019 Category: Standards Track ISSN: 2070-1721 ISDN User Part (IS...