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DTMF tones not recognized

DTMF tones not recognized

DTMF tones not recognized

I currently have a Cisco CUCM and Nortel CS1K setup and when Nortel calls our helpdesk DTMF tones are not recognized. The real strange part is that it is only sometimes it is not recognized. External calls work all the time. Not sure where to start troubleshooting. Any debugs to be run?

We have a Cisco CUBE that connects to the CS1K via a T1 connection. SIP connection between call manager and Nortel.

RE: DTMF tones not recognized

First thing would be to isolate the source(s) of the calls and the call path.
Is it calls from the CS1K or from CUCM?
Is the Helpdesk connected to CUCM or CUBE or CS1K?
Are there multiple routes between the systems?

Are all the calls with DTMF issues limited to certain handset types or are they connected to a particular card or shelf?

The most obvious thing to check would be the DMTF settings on each end of the SIP trunks to check they match (In band or Out of Band RFC2833)
I have also seen issues due to the DTMF length being too short.

RE: DTMF tones not recognized

Turns out I had an MTP configured improperly so the helpdesk and Cisco voicemail now works all the time. But I still have an issue when entering tones via a cell phone for our conference now line. Tones are not recognized. And our Nortel voicemail is only accessible from certain cell phone carriers.

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