Ericsson jdrosen.net Bell Labs/Alcatel-Lucent Proxy servers play a central role as an intermediary in the Session Initiation Protocol (SIP) as they define and impact policies on call routing, rendezvous, and other call features. This document specifies a framework for SIP session policies that provides a standard mechanism by which a proxy can define or influence policies on sessions, such as the codecs or media types to be used. It defines a model, an overall architecture and new protocol mechanisms for session policies. [STANDARDS-TRACK]