https://app.kbone.net/vault/rfc/docid/6675
RFC6140: Registration for Multiple Phone Numbers in the Session Initiation Protocol (SIP)
Internet Engineering Task Force (IETF) A.B. Roach Request for Comments: 6140 Tekelec Updates: 3680 March 2011 Category: Standards Track ISSN: 2070-1721 Registration fo...