This Arduino hackaphone was never going to be pretty, but it does the job

Okay, we'll admit that it looks a bit like a baby monitor. But in contrast to those over-engineered pieces of parenting paraphernalia, this DIY cellphone can actually make calls and send texts over GPRS. More importantly,Hackaday claims it was put together by a lone hacker ("Victorzie") from an assortment of off-the-shelf and modded parts, including a TFT touchscreen, lithium ion battery, charging circuit, GPRS module and shield. These components were hooked up to an Arduino Uno microcontroller running a barebones UI and then jammed into a 3D printed case, which makes the device look far more pocketable than some previous hackaphone efforts. The end result inspires big respect for the creator, but also, more grudgingly, for the pro engineers at places like Nokia, who can pull all this stuff together and even get it FCC-approved for just a few dollars.

Engadget