GoKawiilOpen-source RotaryCell kit turns vintage rotary phones into LTE devices via ESP32-S3
A hobbyist project called RotaryCell adds internal electronics to an unmodified rotary telephone, letting it place calls over LTE using an ESP32-S3-based LilyGO board, a battery, and the AG1171 ringer chip, while keeping the original handset, dial, and hook intact. The current release is a documented, hand-wired working prototype on firmware v0.10.4, with new integrated PCBs already ordered from JLCPCB but not yet assembled or validated.