This powerful Arduino shield contains all the features of your average mobile phone. Once you add your own SIM-Card, you can make phone calls, send SMSs, and even connect to the internet! Two 3.5mm audio jacks connect a speaker and microphone for voice calls. A SIM-card holder is located on the underside of the board (SIM-Card not included). •   Quad-Band 850 / 900/ 1800 / 1900 MHz •   SIM900 Chipset •   Includes SMA Antenna •   Protocol: AT-Commands via Serial/UART •   Dimensions: 85(W) x 57(D) x 18(H)mm (Excluding Antenna)