Asterisk IP Based Trunk DTMF not heard

[raymond.norton]

I have configured an IP-based Asterisk trunk on a v20 on-premise 3Cx install to pass DTMF tones to target zones on a Bogen intercom system. The trunk is operational, and calls are successful, but although Wireshark shows rtpevents are present when running captures on the Fortigate firewall, the DTMF tones cannot be heard on the test calls.

 

[leejor]

What Codecs are you using on the trunk? That, and changing the DTMF type, may make a difference

 

[raymond.norton]

g.711 and g.722 . I have changed the dtmf mode to inband, auto, rfc4733, and info. I verified that g.711 and .722 are loaded on my test Fanvil and Snom phones, but nothing has worked. Payload event is 101

 

[leejor]

If you choose INBAND, then the Codec choice should be G711. Low bandwidth Codecs tend to distort audio DTMF.

 

[raymond.norton]

Inband is where I started.

 

[YiannisH_3CX]

RTP Event signals cannot be heard in the audio as they are not part of the audio stream. Those are out of band signals. Same with SIP INFO. The only tones you will be able to hear are inband tones and you should use G711 for those. But if your trunk is negotiating for telephone-event 101 then you should stick to that.

It looks like you are trying to receive DTMF tones on your 3CX so I would recommend also running a capture on 3CX to see if the signal is reaching you and if 3CX passes DTMF to the device. Also it is very important to see what is negotiated between 3CX and the intercom system to see if the same method is also supported by the intercom.

 

[raymond.norton]

That info is helpful! I only wish I had asked this question in the first 10 hours I was pounding on this issue. The rtpevents do make it to the 3CX server. From the documentation, I understand the ATA attached to the Bogen unit will convert the rtpevents back to DTMF, precisely what I need it to do.

Thank you!