DTMF Issue in 7936 IP Conference Phone

[edwinchungath]

All 7936 IP conference phone the DTMF service is not working through SIP trunk but at the saem time all other IP phones (7941, 7941 etc..) are working DTMF through trunk.

The firmware image is the latest image (cmterm_7936.3-3-20-0)

Any idea what could be the reason.

[Felipe Garrido]

What type of dtmf relay is negotiated between CUCM and the SIP trunk? Can you collect a packet capture off of the 7936?

-Felipe

[edwinchungath]

Dear Felipe,

Please find the attached wireshark sniffer out put.

172.16.21.126 is the IP Conf IP address.

Edwin

[Steven Holl]

I assume this works for other IP phone types?

Unlike most other IP phones, the 7936 doesn't have native RTP-NTE support.  Hence, when a call comes in from the SIP trunk and negotiates RTP-NTE, CM needs to invoke an MTP in order to translate the RTP-NTE from the media stream to SCCP signaling to the IP phone (and vise-versa).

If you have an RFC2833 capable MTP for the codec being used on the MRGL for the SIP trunk, DTMF should work.  If you are invoking an MTP and you still see issues, get:

* Packet capture off of MTP

* Debugs from gateway:

debug voip ccapi inout

debug ccsip mess

debug voip rtp sess name

[edwinchungath]

Hi,

We raised a TAC case with Cisco and finaly conclude its a Bug (defect CSCsu63797 ) in the running ver. (6.1.1)

The issue resolved after upgrade CUCM Image to 6.1.3

Thank you all...

[Kudur MohanRaj]

Hi Steven,

I am having the same issue, I have configured MTP also. But still not working for me.

My connectivity is CUCM sends the call to H.323 Gateway. Then that router which is configured with sip dial peer communicates with ISP.

I have configured MTP with G.729 codec, as well as Transcoder given both to device pool and H.323 gateway. Call gets disconnected with busy tone.

DN: 32893

phone MAC: 0004F2E0A405

I am also attaching the CUCM trace for the same.

Any help is appreciated. Thank you.