It used to be possible on the OpenMoko with asterisk. Have a look at chan-quectel which is targeting similar quectel modem modules, and seems a fair starting point:
https://github.com/t4rd15/asterisk-chan-quectel
The trick will probably be sorting out the audio routing/configuration - Megous has the best description I've seen of how the routing works, or at least can work - I'm not sure if the distros are all doing it the same way.
https://xnux.eu/devices/feature/audio-pp.html
https://github.com/t4rd15/asterisk-chan-quectel
The trick will probably be sorting out the audio routing/configuration - Megous has the best description I've seen of how the routing works, or at least can work - I'm not sure if the distros are all doing it the same way.
https://xnux.eu/devices/feature/audio-pp.html