DTMF (inband) Deutsche Telekom All-IP problem

We are running a asterisk IVR system controlled by dtmf

Every “normal” provider uses rfc2833 to transmit keystrokes which works fine

“Deutsche Telekom” in germany introduced some time ago so called ALL-IP product. This meanes Telekom switches to VOIP

Problem is that asterisk does not recognize dtmf keystrokes. Reason seams to be, that telekom does signal rfc2833 but sends keystrokes only as DTMF-inband

FreeSwitch seems to have a feature called “spandsp_start_dtmf”. Using this FreeSwitch can (not tested) recognize rfc2833 and inband in parallel.

Is there some solution for asterisk?

I tried sip and pjsip (with 13.9.1) but inband is not recognized.

What happens if you explicitly set the configuration to inband? Does it then work? Do you need to send in RFC2833, but accept inband?

Thank you for your answer.

Setting fixed to inband results in randomly duplicate DTMF digits when using non-telekom line. And i can not garantue that all other clients support inband DTMF. Telekom client works fine with inband.

And … in my opinion out-of-band signalling is the future and DTMF-Inband is deprecated. I can not understand why telekom decided to use inband …

Does Deutsche Telecom uses Huawei IMS softswitch?

Sorry i do not know. How can i check this? Is this transmitted in SIP headers?

Any Ideas? I need to detect RFC2833 and INBAND Tones in parallel …