Applicable Standards

RFC 3265, Session Initiation Protocol (SIP)-Specific Event Notification, outlines a framework within which a SIP node, designated as the subscriber, can request automatic, asynchronous notification of certain events from a remote peer, designated as the notifier. RFC 3265 also defines an Event Package as a set of state information to be reported by a notifier to a subscriber, and mandates that such Event Packages be described in a specific RFC explicitly identifying the state information to be reported by the notifier and defining required syntax and semantics to support the subscription/notification exchange.

RFC 3680, A Session Initiation Protocol (SIP) Event Package for Registrations, fulfills this requirement by defining a method that enables SIP user agents to request a defined set of state information from a SIP Registrar.

Section 5.2.3 of the 3GPP (Third Generation Partnership Project) 24.229, IP Multimedia Call Control Protocol Based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP); Stage 3, mandates that a P-CSCF subscribe to the SIP Event Package for Registrations as defined in RFC 3680.