using a mp3 trigger, and getting into the matrix circuit behind the keypad (luckily the phone was OPEN and not locked) we’re going to allow people to pick up the phone
The payphone is so much simpler than I thought! the coin slot is just a bunch of gears, then the circuitry for the buttons and the receiver etc… nice
So I soldered some wires onto the already working switch so when the receiver is picked up a dial tone plays, then working on the matrix to activate different tracks when I button is pressed
the mp3 trigger is pretty simple with a micro sd card, FAT 16 formatted (<2 gb)- either it can be digitally controlled, by closing the switch on pins 0-17 (which switches between 18 tracks), Or it can interface with arduino serially.