https://app.knowbase.one/vault/rfc/docid/6441
RFC5923: Connection Reuse in the Session Initiation Protocol (SIP)
Internet Engineering Task Force (IETF) V. Gurbani, Ed. Request for Comments: 5923 Bell Laboratories, Alcatel-Lucent Category: Standards Track R. Mahy ISSN: 2070-1721 Unaffiliated ...