The DIY Cellphone is a working (albeit basic) cellphone that you can make yourself. It can make and receive phone calls and text messages, store names and phone numbers, and display the time. It builds on the hardware and software in the Arduino GSM Shield but extends it with a full interface, including display, buttons, speaker, microphone, etc. The source files for the cellphone are hosted on GitHub (hardware, software), which also includes an issue list where you can file bug reports or request enhancements.
There are two main variants of the DIY cellphone: one that uses a black and white LCD like those found on old Nokia phones and one that uses an eight-character matrix of red LEDs. The LCD shows more information (six lines of fourteen characters) but breaks over time. The variant with the LED matrix is harder to use but the display is more robust.
Making the Phone
Making the DIY cellphone can be a fairly involved process but it doesn’t necessarily require specific electronics expertise. You’ll need to order the circuit board and electronics components (about $200 total) and have access to some other electronics tools. There’s a good amount of fine hand soldering to be done: about 60 components, mostly surface-mount, which can take from one to five or ten hours, depending on your experience. Programming and, especially, debugging the phone can take a while – again, depending on your experience and how much goes wrong. Making the case requires some plywood and veneer, along with access to a laser cutter (or you can find your own way to enclosure the circuit board). In short, this is a difficult but potentially do-able project.
The design files and source code for the cellphone can be found on GitHub: