SIP-TO-XMPP (stox)

Last modified: 2017-01-25

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Applications and Real-Time Area Advisor

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General Discussion:

Description of Working Group:

Problem Statement

The IETF has defined two signalling technologies that can be used for multimedia session negotiation, instant messaging, presence, file transfer, capabilities discovery, notifications, and other types of real-time functionality:

  • The Session Initiation Protocol (SIP), along with various SIP extensions developed within the SIP for Instant Messaging and Presence Leveraging Extensions (SIMPLE) Working Group.
  • The Extensible Messaging and Presence Protocol (XMPP), along with various XMPP extensions developed by the IETF as well as by the XMPP Standards Foundation.

SIP has been focused primarily on media session negotiation (e.g., audio and video), whereas XMPP has been focused primarily on messaging and presence. As a result, the technologies are mostly complementary. However, there is also some overlap between SIP and XMPP, since there are SIP extensions for messaging, presence, groupchat, file transfer, etc., and there are XMPP extensions for multimedia session negotiation. This overlap has practical implications, since some deployed services use SIP for both media and messaging/presence, whereas other deployed services use XMPP for both messaging/presence and media. When such services wish to exchange information, they often need to translate their native protocol (either SIP or XMPP) to the other protocol (either XMPP or SIP).

Implementers needing to perform such protocol mappings have often worked out their own heuristics for doing so. Unfortunately, these heuristics are not always consistent, which can lead to interoperability problems.


To make it easier for implementers to enable interworking between SIP-based systems and XMPP-based systems, several Internet-Drafts have defined guidelines for protocol mapping between SIP and XMPP, starting with draft-saintandre-xmpp-simple-00 in early 2004. The current documents are:


Those documents are fairly stable and the authors have received feedback from a number of implementers over the years. However, implementers do not always know that such mapping specifications exist, because they are Internet-Drafts and sometimes they have become expired due to inactivity. Thus it would be helpful to publish a set of mapping specifications as RFCs; the foregoing Internet-Drafts provide likely starting points, but other proposals are welcome as per normal IETF working group processes.

It might also be helpful to at some point publish additional documents in the same series, covering topics like capabilities discovery and file transfer. However, any such work would require a recharter.

The group shall not be tasked with defining any new protocols, only with specifying mappings between existing protocols that have been defined for SIP and XMPP.


  1. Address mapping and error handling
  2. Presence mapping
  3. Mapping for single instant messages
  4. Mapping for one-to-one text chat sessions
  5. Mapping for multi-user text chat sessions
  6. Mapping for media signaling

All of the foregoing deliverables are standards track, since they are subject to interoperability testing.

Goals and Milestones

Oct 2013 Submit mapping specifications to the IESG
Aug 2013 Start Working Group Last Call on mapping specifications
Jun 2013 Accept starting-point mapping specifications as WG items

No Internet-Drafts

Request for Comments


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