Rotary phones haven’t been popular for several decades, which means there are at least a couple generations of our readers who may not have ever used one. They provided the same functionality as the push-button landline phones that replaced them, but required that the use hold down a number and rotate it around for it to register. That generated the tones that told the phone company what number you were trying to reach. Now, Redditor LegendaryTangerine has made a vintage rotary phone work with a Raspberry Pi.
LegendaryTangerine hasn’t provided many details about how this is actually setup, but it seems that the Raspberry Pi Zero W is able to detect which numbers are being dialed. It can then ring the electromechanical bell via a MOSFET controlled by the Raspberry Pi’s GPIO pins. It’s not clear if the receiver is connected to the Raspberry Pi or not, but that theoretically could be done in order to place VOIP calls. Or, it could be used to trigger any functions on the Raspberry Pi, such as controlling IoT devices.