RS232 based GSM/GPRS modem is built using SIM900. It works on frequencies of 850MHz, 900MHz, 1800MHz and 1900MHz. The size of it is compact and is basically designed with RS232 level converter circuitry. Here the baud rate range is 9600-115200.
At initial stage, the modem is in Autobaud mode. The modem has internal TCP/IP stack via GPRS. Als