NT2017: Rotary Cellphone

A few years ago, I had the idea that I could build a rotary cellphone. I am not the first to have this idea, nor am I the second. Nor will I be the last. I remember gathering up the parts, when the hackaday article on Mr. Volt's design debuted.

My approach was to cram an Adafruit Feather Fona into a Northern Telecom NT1967 lineman's test set. The part was backordered, so I opted for the stand-alone version of the Fona first. Initial experiments were unsuccessful, so when Feather Fonas restocked, I snagged one. With the addition of a small OLED display, and an 18650, I stitched together a crude almost-functional phone in early 2017.

I brought it with me to VCF East XII, and jury-rigged it to work the night before the event began. It seemed to be a hit, but it still had its share of issues. After that, I shelved the project for awhile.

In the months prior to DEFCON 26, I decided it would be the ideal phone to carry around the convention space. A smart phone is an easy target at such an event, but a dumb phone makes things interesting. So I cracked it back open, and begin fixing the hardware and software issues where necessary. It still has some interesting problems, primarly having to do with the faux-dialtone and audible ringing. I found that I prefer the vibrate feature for call indication, and added an appropriate motor.

The result is this heavy, green beast. It cannot text, its caller ID never works right, it's 2G. But the battery life is insanely long, and it makes for a great conversation piece. When you do find signal, there is great fun to be had in dialing up a friend using a rotary dial.

I'm quite proud of it.

This page was last updated on 2-12-2020
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