[poprhythm]’s Touch Tone MIDI Phone is a fantastic conversion of an old touch tone phone into a MIDI instrument complete with intact microphone, but this project isn’t just about showing off the result. [poprhythm] details everything about how he interfaced to the keypad, how he used that with an Arduino to create a working MIDI interface, and exactly how he decided — musically speaking — what each button should do. The LEDs on the phone are even repurposed to blink happily depending on what is going on, which is a nice touch.

Of course, it doesn’t end there. [poprhythm] also makes use of the microphone in the phone’s handset. Since the phone is now a MIDI instrument with both a microphone and note inputs, it’s possible to use them together as the inputs to vocoder software, which he demonstrates by covering Around the World by Daft Punk (video).

We love how [poprhythm] explains how he interfaced to everything because hardware work is all about such details, and finding the right resources. Here’s the GitHub repository for the Arduino code and a few links to other resources.

We have seen MIDI phone projects before, and each one is always unique in its own way: here’s a different approach to converting a keypad phone to MIDI, and this rotary pulse-dial phone went in a completely different direction with the phone itself completely unmodified, using only external interfacing.

You can admire [poprhythm]’s Touch Tone MIDI Phone in action in the short videos embedded below, with each one showing off a different aspect of the build. It’s great work!