The Arduino GSM Shield allows an Arduino board to connect to the internet, make/receive voice calls and send/receive SMS messages. Just plug this module onto your Arduino board, plug in a SIM card from an operator offering GPRS coverage and follow a few simple instructions to start controlling your world through the internet. You can also make/receive voice calls (you will need an external speaker and microphone circuit) and send/receive SMS messages.

The Shield uses a radio modem M10 by Quectel. It is possible to communicate with the board using AT commands. Use the GSM library to learn more about how to make sketches using one or more of the functions described. Arduino boards use digital pins 2 and 3 for software serial communication with the M10. Pin 2 is connected to the M10's.

TX pin and pin 3 to its RX pin. The modem's PWRKEY pin is connected to Arduino pin 7. The M10 is a Quad-band GSM/GPRS modem that works at frequencies GSM850MHz, GSM900MHz, DCS1800MHzand PCS1900MHz. It supports TCP/UDP and HTTP protocols through a GPRS connection. GPRS data downlink and uplink transfer speed maximum is 85.6 kbps. To interface with the cellular network, the board requires a SIM card provided by a network operator. See the getting started page for additional information on SIM usage.

The most recent revision of the board uses the 1.0 pinout on rev 3 of the Arduino UNO board.

On board indicators

The shield contains a number of status LEDs:

• On: shows the Shield gets power.
• Status: turns on to when the modem is powered and data is being transferred to/from the GSM/GPRS network.
• Net: blinks when the modem is communicating with the radio network.

On board interfaces

The shield supports AIN1 and AOUT1 as audio interfaces; an analog input channel and an analog output channel. The input, exposed on pins MIC1P/MIC1N, can be used for both microphone and line inputs. An electret microphone can be used for this interface. The output, exposed as lines SPK1P/SPK1N, can be used with either a receiver or speaker. Through the modem, it is possible to make voice calls. In order to speak to and hear the other party, you will need to add a speaker and microphone.