http://www.rfc-editor.org/rfc/rfc3487.txt
RFC 3487: Requirements for Resource Priority Mechanisms for the Session Initiation Protocol (SIP), H. Schulzrinne2003-02-01T23:00:00-00:00This document summarizes requirements for prioritizing access to circuit-switched network, end system and proxy resources for emergency preparedness communications using the Session Initiation Protocol (SIP). This memo provides information for the Internet community.