[asterisk-users] SIP kpml DTMF support in *

[Dan Austin]

Grigoriy wrote:

> I'm trying to connect Asterisk 1.4 and Cisco CallManager 5 
> using SIP Trunk without MTP (media termination point). 
> Howerver, Cisco 79xx phones do not support RFC2833, they 
> always notify CCM5 via SKINNY channel no matter where they
> send RTP to.
If you are running the phone loads that shipped with CCM5,
then your skinny phones have 'support' for RFC2833.  CCM
figures out during the call if the call will traverse a
SIP trunk and instruct the phone to use RFC2833 for DTMF
I have a CCM5<->Asterisk trunk setup for MeetMe conferencing
with NO MTP and DTMF works fine.

> For non-MTP trunk there's Out-of-band DTMF support in CCM5 
> called "kpml". I wonder if Asterisk can support it.
Interesting, will look it up...

> I found an intertnet-draft for kpml:
> http://tools.ietf.org/id/draft-ietf-sipping-kpml-07.txt, but
> it seems to be very old - "Expires June 25, 2005".

> I know that using MTP in SIP Trunk at CCM5 makes DTMF work 
> in RFC2833, but MTP resource is very limited and I don't want 
> to proxy RTP via CCM5.
I don't blame you, nut again as of CCM5 you are no longer
required to use an MTP for SIP trunks.

> Please, do not offer to use H.323.
OK, not an offer, but I have found that even as of the latest
CCM5 release, the SIP stack is 'quirky'.  I also maintain
a H323 trunk between the same CCM cluster and Asterisk and
in general it is much better behaved (using chan_ooh323).
Either will work....

Dan