GSM modules

SIM900 Four Band GSM GPRS Module with Antenna shield for Arduino features:
- GSM / GPRS SIM900 module-based development card / shield from Simcom
- The shield allows you to get SMS, MMS, GPRS and audio via UART by sending AT commands (GSM 07.07, 07.05 and SIMCOM Enhanced COM Commands).
- The shield also has 12 GPIOs, 2 PWMs and a ADC of the SIM900 module (All of them are 2V8 logic) present on board.
- Quad-Band 850/900/1800/1900 MHz: it would work on GSM networks in all countries of the world. - GPRS multi-slot class 10/8
- GPRS mobile station class B
- Complies with GSM phase 2/2 +
- Class 4 (2 W @>

GSM A6 Four Band GPRS Module with MCU Antenna features:
- GSM / GPRS module / development board / shield based on GPRS A6
- Supports GSM / Dual band GPRS, available for remote GPRS and SMS data transmission
- Compact size and low current consumption
- With energy saving technique, current consumption is as low as 5mA (sleep mode)
- Communicates with the microcontroller through the UART port, supports the command including GSM 07.07, GSM 07.05 and Ai-Thinker Enhanced AT Commands
- Working frequency: four-band network, 850 / 900/1800 / 1900MHz
- Operating voltage: 4.8-9VDC (Supply power of the on-board regulator circuit for the A6 module)
- Working current: 2A maximum
- Current Sleep: 5mA

The SIM800A modem is based on SIMCOM's dual band GSM / GPRS.