IPv6 Transition in the Session Initiation Protocol (SIP)
This document describes how IPv4 Session Initiation Protocol (SIP) user agents can communicate with IPv6 SIP user agents (and vice versa) at the signaling layer as well as exchange media once the session has been successfully set up. Both single- and dual-stack (i.e., an IPv4-only and an IPv4/IPv6) user agents are considered.