[Linphone-developers] Detecting DTMF ( dual tone multi-frequency ) from incoming raw pcm data

[Davis Roman]

Hello,

We're working on an embedded Linux device with cellular radio capabilities.

Once a voice call is initiated, the PCM output of the radio is routed
into the kernel and it appears as a regular alsa sound device.

When linphone is running, we set the soundcard corresponding to the
GSM cellular radio.

At this point, linphone initiates a voip call with a remote sip client
and now an end to end connection is established.

I know that linphone can detect DTMF tones from the SIP client however
I'd also like to detect DTMF tones coming from the cellular user.

Can linphone detect DTMF tones by looking at the raw incoming PCM data?

Thank you,

Davis