RotaryCell

RotaryCell converts a traditional rotary telephone into a self-contained, battery-powered, portable cellular telephone without modifying the original telephone .

The design continues to use the original handset, rotary dial, switch-hook, mechanical ringer, network block, and existing jacks. The added electronics mount reversibly inside the case; no original telephone parts need to be drilled, cut, or permanently altered.

The working prototype can be carried and operated away from a fixed telephone connection, making the original desk telephone usable at meetings, demonstrations, or anywhere compatible cellular service is available.

This is a working engineering archive rather than a finished construction release. The hand-wired prototype operates, while the first integrated PCBs are currently awaiting assembly and validation.

Open or download the full-resolution printable PDF . It covers the LilyGO, protected 21700, passive audio components, AG1171, GPIO connections, and original Model 500 circuitry without using the new PCBs. A hand-wired installation fits inside the telephone, but arranging and insulating all of the loose components and wiring is challenging; expect repeated dry-fitting and careful routing.

The Audio and Reset A4 PCB was ordered from JLCPCB on August 27, 2026.

The AG1171 Carrier Through-Hole PCB was ordered from JLCPCB on August 28, 2026.