This document specifies the Diameter Session Initiation Protocol (SIP)
Application. This is a Diameter application that allows a Diameter client
to request authentication and authorization information. This application
is designed to be used in conjunction with the Session Initiation Protocol
(SIP), and provides a Diameter client co-located with a SIP server, with
the ability to request the authentication of users and authorization of SIP
resources usage from a Diameter server.