[Jingle] XEP-0181: Jingle DTMF

Robert McQueen robert.mcqueen at collabora.co.uk
Wed Jul 23 19:16:10 CDT 2008

Johansson Olle E wrote:
> I agree that in most situtations, DTMF in the media stream is to be
> preferred, mostly because
> of timing issues. In some cases, DTMF is handled out of band for IVR
> situations, then maybe
> KPML could be used in the XMPP stream. It's an XML-based definition in
> RFC 4730.

What IVR situations can't just process the events out of the RTP stream
in order to find out what DTMF is being sent? I don't think this is a
compelling argument for either a) requiring clients to implement two
DTMF methods, or b) preventing DTMF interoperation between normal Jingle
and SIP endpoints unless the gateway does extra work.

> Please also note that 4733 REQUIRES use of SRTP, where RFC 2833 doesn't.
> That's propably why most SIP devices still only claim support of 4733.

I think 2833-compliant endpoints can still exchange telephony events
with 4733-compliant endpoints. It'd be pretty broken if that wasn't the
case. And it doesn't REQUIRE the use of SRTP, it just says this:

   To meet the need for protection both of confidentiality and
   integrity, compliant implementations SHOULD implement the Secure
   Real-time Transport Protocol (SRTP) [7].

When we can signal SRTP, we'll probably say the same kind of thing too. :D

> /Olle


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