I've been trying to find any information about if an idea I've had for a project is possible with this or any other module attached to an arduino and so far I haven't found anything. I want to convert an old 70s deskphone to a modern sim-based phone. I understand that GSM modules are usually for GPS and alerting and the docs for the GSM 1400 explicitly state that it can't connect devices for "real" calls. I was wondering if anyone has either found a way to make a phone work with a GSM module or if anyone knows if it is possible?
For my project I guess it would need to connect a board to the dial buttons, have a microphone and a speaker for the call (and possibly another speaker for the ringing).