RotaryCell Lets a Classic Rotary Phone Make Calls Over LTE
A new open-source hardware project called RotaryCell shows how to keep an old-school rotary phone fully functional in 2024 by pairing it with an ESP32-S3 microcontroller and an LTE modem. The board taps into the phone's original pulse-dialing and ringer circuitry, translating rotary dial pulses into standard cellular call commands, so the physical phone itself needs no rewiring or modification.
The project is aimed at hobbyists and retro-tech tinkerers who want a genuinely working landline replacement using nothing but a cell signal, rather than VoIP or a traditional phone line. Because it's built around a widely available microcontroller and documented in the open, others can replicate or extend the design for their own vintage phone collections.
It's a niche build, but a clever demonstration of bridging analog-era hardware with today's networks using cheap, accessible components.