Usage of the Session Description Protocol (SDP) Alternative Network Address Types (ANAT) Semantics in the Session Initiation Protocol (SIP)
This document describes how to use the Alternative Network Address Types (ANAT) semantics of the Session Description Protocol (SDP) grouping framework in SIP. In particular, we define the sdp-anat SIP option-tag. This SIP option-tag ensures that SDP session descriptions that use ANAT are only handled by SIP entities with ANAT support. To justify the need for such a SIP option-tag, we describe what could possibly happen if an ANAT-unaware SIP entity tried to handle media lines grouped with ANAT. [STANDARDS-TRACK]