Analog Redial lets a rotary phone ring the other room, or read pi when you dial 314

Dial 314 and an old telephone reads pi aloud. Dial another code and it can ring the phone in the next room. The rotary dial finally has a job beyond confusing younger relatives.

Analog Redial’s maker built an ESP32-C6 board that handles rotary pulses and touch tones, supplies telephone-line signals and serves a configuration page in a browser. Its offline mode needs two phones and a second line on the board. Optional network calling can link boards directly or use a SIP server.

The published October 2026 estimate is about $37 per single-line board in a five-board order; the second line adds about $10. Ordering for one build has a higher upfront cost because the PCB order has a five-board minimum. The firmware is MIT-licensed and the hardware files are available in KiCad.

The browser interface gives those codes somewhere to live. The README puts it at http://phone.local; on first boot, the board creates a setup network so you can connect it to your own Wi-Fi. The page manages recordings and dial codes. A museum exhibit could have its own audio attached to a number, without making visitors install an app just to lift a handset.

A few built-in numbers suggest how far that can go. The README lists 412 for dial-up modem sounds, 846 followed by a number of minutes for a timer, and 256 followed by a time for an alarm. A phone that interrupts you because dinner needs checking is a fairly convincing retirement plan for the family landline.

There are configuration choices to settle before ordering. The current design’s microSD storage option is for a single-line build; the two-phone intercom needs the second line. Bluetooth calling takes an additional module. A feature being in the README doesn’t mean every possible combination fits the board you are about to assemble.

The assembly guide also divides the work sensibly: the fabrication service installs the surface-mount components, while the builder solders the through-hole parts and flashes the firmware. That still leaves a real build to finish. The maker’s instructions, rather than a photograph of the completed case, are the place to decide whether this belongs on your bench.

Home Assistant events over MQTT or webhooks are labeled “Experimental”. A dialed command could switch a light, but that integration still deserves a test before it gets a household job.

A browser full of configurable codes gives the old dial room for new tricks. The interesting next build is the one where the physical act of dialing makes more sense than opening an app.