From Make: technology on your time

Portable Rotary Cell Phone

The Portable Rotary Phone is a GSM cell phone built inside an old rotary phone. With a little tinkering….

Take the old phone apart

Add a little of this and a little of that

You pop your SIM card in, it dials out, rings and acts just like an old fashion phone, but it's now my full time cell phone.

If you don’t want to take the time and frustration of figuring out how to do it on your own, you can buy one at Spark Fun for $400 + tax and shipping