PiGraham wrote: ↑Thu Mar 15, 2018 4:16 pmThat's what "voice modems" were for. Seems you can still buy such things.
They should operate as serial devices.
"AT commands" allow control for off hook, dial DRMF, send audio data etc.
https://en.wikipedia.org/wiki/Voice_mod ... ansmitting audio_data
Why is that line in the code?
All the usual places. I ordered mine at https://thepihut.com/products/raspberry ... del-b-plus