The RePhone system from Seeed is a customizable modular GSM, GPRS phone system with Bluetooth support. The basic phone consists of a tiny circuit board with a SIM slot. The whole thing is open source so you can hack away to your heart’s content. Add-ons include a 1.54-inch touchscreen, LEDs, a 520mAh battery and an NFC chip for wireless pairing with speakers and other accessories.

The modules can be configured in a number of different ways and connect via FPC ribbon cables, conductive thread, soldered wires or even by breadboarding.

There are two main Core boards; the RePhone Core GSM + BLE module or the RePhone Core 3G module which gives faster data throughput but no BLE support. Eight add-on boards from Seeed’s Xadow series provide a 1.54-inch touch screen, 5×7 LEDs, NFC, GPS, audio, a sensor board, a GSM breakout board and an Arduino-compatible microcontroller.

As well as the hardware, Seeed has also developed library support for the Arduino environment, Lua and Javascript to allow you to connect the phone to the web, IFTTT and a full SDK based around Eclipse for C/C++ developers. Seeedstudio recently struck a deal with Massimo Banzi of Arduino to produce Arduino products in the Far East. The RePhone is also compatible with Seeed’s Pebble Time smart strap wearable. The RePhone project has been launched on Kickstarter, the basic Core board retails at $12 and the Create kit is around $50