SIMCom SIM900 Quad-band GSM/GPRS module support 850/900/1800/1900MHz network for voice, SMS, data, and Fax. It looks for the correct frequency automatically. We develop this board to make it convenient for you to work with Arduino or other MCU board. The information of this board are as below. Summary: This board is a new designed, easy to use SIM900 GPRS shield which is compatible with Arduino. With AT commands, you can control it easily. As for Arduino, there are two serial ports to communicate with it, one software serial port(D2/D3) and one hardware serial port(D0/D1).You can select any one as you want through the jumpers. This board also provids two PWM ports, one ADC port, and 10 GPIOs which can be easily used for your project. There is also a FTDI interface which can be used to interface with the FT232RL board. With its help, you can use your computer to debug it. The main information of this board are as below. Features: Compatible with Arduino Dimensions: 8.1cm*5.4cm Serial port:Can communicate with Arduino through the Software serial port(D2/D3)or the Hardware serial port(D0/D1) FTDI interface. You can use the PC or other host which have an USB port(through FT232RL board) to debug it. Software or Hardware Power ON/OFF. You can Power On/Off SIM900 through an IO of Arduino or an button on the board. Battery slot for RTC. This is useful if you want the time of the module doesn't lose when it is Power Off. SD card slot. Convenient for data save like SMS, GPRS data or any other kind of data. Also can be disabled if you don't want to use it. Then it will have no influence to the arduino ports. 　 PACKAGE INCLUDES 1 x NEW SIMCOM SIM900 Quad-band GSM GPRS Shield for Arduino