Asunflower&reg; SIM900 Quad-band GSM GPRS Shield Development Board for Antenna SIM900 Board Input is 9-36V 2A We Recommended current is more than 9V 2A Note:The SIM900 Board Input is 5-36V 2A,We Recommended current is more than 9V 2A . Ensure your SIM card is not locked , GPRS Shield Communication baud rate is 19200 BPS 8-N-1 Quad-Band 850 / 900/ 1800 / 1900 MHz - would work on GSM networks in all countries across the world. Control via AT commands - Standard Commands: GSM 07.07 & 07.05 | Enhanced Commands: SIMCOM AT Commands. Short Message Service - so that you can send small amounts of data over the network (ASCII or raw hexadecimal). The GPRS Shield is based on SIM900 module from SIMCOM and compatible with Arduino and its clones. The GPRS Shield provides you a way to communicate using the GSM cell phone network. The shield allows you to achieve SMS, MMS, GPRS and Audio via UART by sending AT commands (GSM 07.07 ,07.05 and SIMCOM enhanced AT Commands). The shield also has the 12 GPIOs, 2 PWMs and an ADC of the SIM900 module(They are all 2V8 logic) present onboard.