Sim900a modem is built with dual band gsm/gprs based sim900a modem from simcom. It works on frequencies 900/ 1800 mhz. Sim900a can search these two bands automatically. The frequency bands can also be set by at commands. The gsm/gprs modem is having internal tcp/ip stack to enable you to connect with internet via gprs. Sim900a is an ultra compact and reliable wireless module. This is a complete gsm/gprs module in a smt type and designed with a very powerful single-chip processor integrating amr926ej-s core, allowing you to benefit from small dimensions and cost-effective solutions. Sim900a features - gprs multi-slot class 10/8 - gprs mobile station class b - compliant to gsm phase 2/2+ - class 4 (2 w @850/ 900 mhz) - class 1 (1 w @ 1800/1900mhz) - control via at commands (gsm 07.07, 07.05 And simcom enhanced at commands) low power consumption: 1.5Ma(sleep mode) operation temperature: -40°c to +80 °c specifications for gprs data : gprs class 10 max. 85.6 Kbps (downlink) max. 42.8 Kbps (uplink) pbcch (support packet switched broadcast control channel) support coding schemes cs 1, 2, 3, 4 specifications for sms via gsm/gprs - point to point mo and mt - sms cell broadcast - text and pdu mode software features - 0710 mux protocol - embedded tcp/udp protocol - ftp/http - fota - mms - embedded at compatibility: at cellular command interface sim900a rs232 + ttl board features input voltage: 12v on board power led on board network led rs232 serial control (tx and rx) modem reset pin out default baud rate: 9600. Databits: 8, parity: none, stop bit: 1 pcb board specifications material: fr4 (high quality) board thickness: 1.6Mm.