How to trace DTMF inputs

[allahverdiyev]

Hello,

How can I trace dialed DTMF digits between 2 sip endpoints registered to CUCM? One endpoint is 9971, another one is third-party device which is able to accept DTMF digits and do some actions. 9971 calls thrid-pary device and dial code to do action during the call.

Thank you for your answers.

[Balram Vishwakarma]

Hello,

Please follow below document to understand.

https://supportforums.cisco.com/t5/collaboration-voice-and-video/understanding-dtmf-negotiation-and-troubleshooting-on-sip-trunks/ta-p/3152511/jump-to/first-unread-message

[allahverdiyev]

In all scenarios are related to trunk. I am asking about both parties are registered devices, not trunk.

[Jonathan Schulenberg · Accepted solution]

Same basic concepts apply: either the DTMF events are out-of-band and visible in the SIP dialog (eg KPML) or in-band as NTE packets in the RTP stream (eg RFC2833). A packet capture will plainly show both assuming the call isn’t encrypted.

[allahverdiyev]

thank you for answer.

Just 2 questions:

1. How can I define whether it is OOB or in Band between 2 registered endpoints? Again, there is not sip trunk. It is single cluster.

2. Packet capture is the only way to trace DTMF inputs?

[Balram Vishwakarma]

As Jon mentioned, same concept applies between endpoint as well.

You need to check the traces and logs to find out if its OOB or IN-Band DTMF is being used.

9971 supports both OOB and IN-Band DTMF and most of the case IN-Band unless changed from configuration side forcefully.

Packet capture and logs both can be used to identify the DTMF method used in the call.

I would suggest you go through the provided document and understand the logic behind it and same it goes for phones as well.