You might find this interesting: https://learn.adafruit.com/piphone-a-raspberry-pi-based-cellphone https://learn.adafruit.com/piphone-a-raspberry-pi-based-cell.

You might find this interesting: https://learn.adafruit.com/piphone-a-raspberry-pi-based-cellphone https://learn.adafruit.com/piphone-a-raspberry-pi-based-cell... There's also an Arduino one: https://learn.adafruit.com/arduin-o-phone-arduino-powered-diy-cellphone https://learn.adafruit.com/arduin-o-phone-arduino-powered-di...