AvrPhone is ATmega128A-based simple mobile phone with touch screen and SIM100S GSM module. The display uses 2,4″ LCD with a resistive touch screen and ILI9325B driver (16 bit parallel bus).
The LCD breakout board contains SD card slot and XPT2046 touchscreen controller. They both are connected to AVR’s SPI bus. The project is powered by 3.7V/1000mAh Li-Po cell.
The user interface provides way to make and receive phone calls, write and read SMS messages, store contacts in contact book (on SIM card) or view some photos.
For more detail: AVR Based Mobile Phone using AVR ATmega128A microcontroller