RE: [Sip] SIP INFO & DTMF

Take a look at the application interaction work:-

http://www.ietf.org/internet-drafts/draft-ietf-sipping-app-interaction-framework-03.txt

in association with the 'Key Pad Markup Language':-

http://www.ietf.org/internet-drafts/draft-ietf-sipping-kpml-07.txt

HTH,

Chris.

-----Original Message-----
From: Jan.Van_Opstal@alcatel.be [mailto:Jan.Van_Opstal@alcatel.be] 
Sent: 08 February 2005 08:15
To: sip@ietf.org
Subject: [Sip] SIP INFO & DTMF

Hi all,

I am currently confused how DTMF digits can be carried via the 
signalling path using SIP. If I am not mistaking, then a SIP INFO 
message should be used, but the confusion that I have is how should 
the content look like ?

There are some drafts, namely:

 -  draft-choudhuri-sip-info-digit-00.txt expired October 2000
 - draft-mahy-sipping-signaled-digits-00.txt expired May 2002

but as you can see, all expired.

Some think RFC2833 should be used withing a SIP message.  But 
it seems rather unlogical to use a sip info message to carry digits as 
explained in rfc2833 which targets rtp packets ... ?

I have checked the implementation of some MGW manufacturers:
Cisco, Snom and AudioCodes all use draft mahy-sipping-signaled-digits-00.txt,
but is this the way to go ? Or is there maybe a new draft or standard
that tell us what to use ?

Thanks in advance,

    Van Opstal Jan
    R&D Alcatel Antwerp, Belgium

Note: 
1) an example of a SIP INFO message using RFC2833:

INFO sip:192.168.50.7:5060 SIP/2.0
From: <sip:496420033@192.168.50.5;user=phone> <mailto:sip:496420033@192.168.50.5;user=phone> ;tag=0082-00000002-0021
To: <sip:025552024@192.168.50.5;user=phone> <mailto:sip:025552024@192.168.50.5;user=phone> ;tag=0082-000000dd-05d1i0
Call-ID: 0082-00000002-00214204b9f1-167e-433ca000@sipua
CSeq: 4 INFO
Max-Forwards: 29
Contact: "sipua" <sip:192.168.50.6:5060>
Content-Type: audio/telephone-event
Content-Length: 4

,2,100

(the body part is not really correct: should be extracted as
explained in RFC2833)

2) an example of a SIP INFO msg using draft mahy-sipping-signaled-digits-00.txt:

INFO sip:2143302100@172.17.2.33 SIP/2.0 
Via: SIP/2.0/UDP 172.80.2.100:5060 
From: <sip:9724401003@172.80.2.100> <mailto:sip:9724401003@172.80.2.100> ;tag=43 
To: <sip:2143302100@172.17.2.33> <mailto:sip:2143302100@172.17.2.33> ;tag=9753.0207 
Call-ID: 984072_15401962@172.80.2.100 
CSeq: 25634 INFO 
Content-Length: 26 
Content-Type: application/dtmf-relay 

Signal= 7 
Duration= 300 

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