DTMF... getting crazy

I’m incurring problems in DTMF asterisk 1.4 - FreePBX 2.3.1 (Trixbox 2.4 machine)

I have 11 telephone numbers registered.
All the numbers expect one work fine with RFC 2833.
With the damned number IVR doesn’t recognize when I digit numbers.
Seems that the DTMF tones are not passed, infact, using a sip client, I discovered that the IVR works fine if I set DTMF in “SIP INFO” mode.

The problem is that I tried to manually change DTMF in extension.conf (dtmfmode=info and dtmf=info). I tried relaxdtmf=yes… nothing change :frowning:
Codec: alaw and ulaw

Any tip?

Thanks in advance,


Is the channel a sip or zap channel? There have been reports of DTMF problems with VTWhite.

Sorry, I forgot to say that the trunk is a sip channel.
Provider is Eutelia (Italian Provider). With all the italian prefex numbers is ok, the “BAD” number is a Swiss number (+41) that Eutelia resell too.


any idea ?

You probably need to contact your provider
Also, try dtmfmode=inband

That helped for me when the IVR was only working for Verizon Wireless cell phones only. Yes, very wierd.