Self-answering Phone
The operator of an escape room asked us to update an old rotary phone so it would play a message if the right number was dialled, and a busy signal if the wrong number was dialled.
We gutted the phone case of unneeded components, determined how to get a signal of the rotary dial and installed electronics for an arduino to read this signal. We replaced the speaker in the headset with one that is headphone compatible. We installed an MP3 player that would play either a dial tone, busy signal, or the message, based on signals from the Arduino. We wrote the software to run a dial tone when the receiver is lifted, interpret the signal to a number dialled, and to play the message or the busy signal based on the number dialed.
