DTMF tones not being detected


I am using Asterisk and experiencing random issues with DMTF tones not working for specific users. For a period of time, I had no idea why it was occurring so instead, I blamed it on my provider. After switching providers, I noticed a brief disappearance with the issue. However, the issue came back. I originally had my dtmfmode in my sip.conf set to “rfc2833” but then changed it to “auto” but it made no difference.

Any ideas?

Please help!


That’s an out of support version. There have been several fixes to DTMF handling since then, although they are about unreliable operation, rather than non-operation.

You need to provide enough tracing information to show exactly what options are being negotiated and how the DTMF is actually being sent. Probably start with sip debugging and the DTMF log. You may need to use something like wireshark.

Hello David,

Thank you for the timely response and the useful information. Is there a guide for newbies on how to debug such DTMF issues?


I don’t know of any.