DTMF with Payload Type 96 not working

[TheYves]

Hello

DTMF on our 3CXPhone is not working if a call is routed through our VoIP/ISDN gateway (bero*fix with BF2S02FXS module). However the problem does not occur with our Panasonic KX-TGP500 DECT phones or if a call is routed to our VoIP provider. Both 3CXPhone and Panasonic are set to out-band DTMF using RFC 2833. So I started analyzing the network traffic with Wireshark and I found out that 3CXPhone is using payload type 96 while the Panasonic is using paylod type 101. As soon as I change the payload type for DTMF on the Panasonic to 96, DTMF doesn't work anymore. Now I'm wondering, if there's any possibility to change the payload type on 3CXPhone to 101 instead of 96. Or is there any other way getting DTMF to work without changing to in-band DTMF?

WORKS: 3CXPhone (payload type: 96) --> VoIP Provider
WORKS: Panasonic (payload type: 101) --> VoIP Provider
WORKS NOT: 3CXPhone (payload type: 96) --> VoIP/ISDN Gateway
WORKS: Panasonic (payload type: 101) --> VoIP/ISDN Gateway

Thanks in advance

 

[leejor]

When dealing with DTMF choices, the 3 common selections are... SIP Info, RFC2833, and In-Band (audio). For most uses, either one, or a combination, (or sometimes "Auto", if available) will work. Your gateway has to be set to match the choice(s) on your devices.

I don't recall any of the VoIP devices, including the 3CX Phone, that I have used, having the selection of DTMF payload type as 96 or 101.

 

[TheYves]

Thanks for your reply. If there's no chance to change the payload type, I have to use SIP-INFO.

But: This is a setting in the 3CXPhone client. How can I change the provisioning template for the 3CXPhone? Or does each user have to change the DTMF setting manually?

 

[leejor]

Never having auto-provisioned the 3CX Phone, I can't answer your question, sorry. Have you looked into "playing around" with the DTMF choices on the ISDN gateway?

 

[TheYves]

Sadly there's no option to change the payload type on the gateway. It's just a passes the DTMF signals through. Well, my only option seems to change DTMF on 3CXPhone to SIP-INFO. :-/