Subject: [dispatch] Topic for DISPATCH: Alert-Info URNs

From: <[email-masked]>
Date: Mon, 14 Sep 2009 11:03:19 +0200

Mary, Gonzalo,

At the IETF-75 we had a presentation and a discussion in BLISS on the "Alert-Info URNs" proposal, described in http://tools.ietf.org/id/draft-alexeitsev-bliss-alert-info-urns-02.txt.  During the discussion, it was recommended to submit the work to DISPATCH and to document the interop problems. 

So, we would like to propose this as a new topic for DISPATCH. 

The motivation for this work comes from interoperability problems when SIP services require the semantic for a ring- / ringback-tone to be transmitted in in a SIP-message.  

The RFC 3261 allows an UAS or proxy to provide a specific ring- /ringback-tone as a reference (e.g. HTTP URI) which can be played to the user in the Alert-Info header. This mechanism does not ensure interoperability when there is no common understanding of the referenced content (different countries or vendors, hearing impaired) or when the user has his own tones configured in the end device. 

For interoperability of services as call waiting, call forwarding, blind transfer, automatic callback, call hold or emergency annoncements sent over PBX systems, a mechanism is needed which allows the UAs and proxies to transmit an indication which contains the semantic of the rendering instead of the rendering itself and allows the receiving UA to decide about the concrete rendering. 

The charter proposal and the updated draft are to follow. 

Kind regards
Laura