RFC 3840 · PROPOSED STANDARD · 2004

Indicating User Agent Capabilities in the Session Initiation Protocol

Overview

RFC 3840, “Indicating User Agent Capabilities in the Session Initiation Protocol”, is a Proposed Standard document published in August 2004 by J. Rosenberg, H. Schulzrinne, P. Kyzivat. The canonical text is published by the RFC Editor.

Abstract

This specification defines mechanisms by which a Session Initiation Protocol (SIP) user agent can convey its capabilities and characteristics to other user agents and to the registrar for its domain. This information is conveyed as parameters of the Contact header field. [STANDARDS-TRACK]

Abstract as published in the RFC, via rfc-editor.org.

What “Proposed Standard” means

An entry-level standards-track specification: stable, peer-reviewed and a solid basis for implementation, though it may still evolve before becoming an Internet Standard.

Read this RFC

The canonical text of RFC 3840 is hosted at rfc-editor.org. Available in TXT,HTML.

Other RFCs from 2004

Who Is Online

In total there are 124 users online: 0 registered, 116 guests and 8 bots.

Most users ever online was 5,555 on 17 Jul 2026, 3:23 am.

Bots: AhrefsBot Applebot Baiduspider Bingbot Other Bot Other Crawler PetalBot SemrushBot

Users active in the past 15 minutes. Total registered members: 372