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SIP rtp-nte DTMF relay tone duration

We have a CUCM routing external calls out through a Cisco IOS H.323 gateway to an ITSP, using SIP for the onward connections.  We are using rtp-nte relay for the dtmf tones and these function on 99% of remote IVR menu systems etc.

We have some remote menu systems that we cannot use however, but the ITSP is insisting the problem is with our PBX (the IOS gateway).  They say the problem is that we are sending the NTE events with a duration of "0".  I cannot see how to configure the length of these, and to be honest I did think that it was the ITSP onward gateways that would translate the NTE packets to a default tone length.

Can I ask if anyone has been in this situation? I could understand if not tones ever got through, but it is baffling that the majority are fine.  The ITSP supports in-band voice tones (no relay) and NTE RFC 2833.

1 Reply 1

This has been resolved - the solution was to add the below command to the dial-peers pointing to the ITSP (SIP trunk).

dtmf-internetworking rtp-nte

It appears to work in conjunction with the dtmf-relay rtp-nte command, and defines a clear beginning and end to each tone.

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