Network Working Group M. Lonnfors Request for Comments: 5196 K. Kiss Category: Standards Track Nokia September 2008 Session Initiation Protocol (SIP) User Agent Capability Extension to Presence Information Data Format (PIDF) Status of This Memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited. Abstract Presence Information Data Format (PIDF) defines a common presence data format for Common Profile for Presence (CPP) compliant presence protocols. This memo defines a PIDF extension to represent SIP User Agent capabilities. Lonnfors & Kiss Standards Track [Page 1] RFC 5196 User Agent Capability Presence Status September 2008 Table of Contents 1. Introduction ....................................................3 1.1. Motivation .................................................3 1.2. Scope ......................................................4 2. Conventions .....................................................4 3. Extension for "Indicating User Agent Capabilities in the Session Initiation Protocol (SIP)" in PIDF Documents ............4 3.1. Overview of Operation ......................................4 3.2. Service capabilities .......................................5 3.2.1. Element ..................................5 3.2.2.