@misc{rfc3680, series = {Request for Comments}, number = 3680, howpublished = {RFC 3680}, publisher = {RFC Editor}, doi = {10.17487/RFC3680}, url = {https://www.rfc-editor.org/info/rfc3680}, author = {Jonathan Rosenberg}, title = {{A Session Initiation Protocol (SIP) Event Package for Registrations}}, pagetotal = 26, year = 2004, month = mar, abstract = {This document defines a Session Initiation Protocol (SIP) event package for registrations. Through its REGISTER method, SIP allows a user agent to create, modify, and delete registrations. Registrations can also be altered by administrators in order to enforce policy. As a result, these registrations represent a piece of state in the network that can change dynamically. There are many cases where a user agent would like to be notified of changes in this state. This event package defines a mechanism by which those user agents can request and obtain such notifications. {[}STANDARDS-TRACK{]}}, }