RotaryCell: Making an unmodified rotary phone work over LTE with an ESP32-S3

RotaryCell is a project that converts a traditional rotary telephone into a portable cellular device using an ESP32-S3 microcontroller and LTE modem, while preserving all original components without any permanent modifications. The working prototype uses an unmodified Model 500 telephone handset, dial, and mechanical ringer, with added electronics mounted reversibly inside the case, allowing the vintage phone to operate as a battery-powered mobile device anywhere cellular service is available. The project is currently at the hand-wired prototype stage with custom PCBs ordered but awaiting assembly and validation.