The "AT" or "at" prefix must be set at the beginning of each command line. To terminate a command line enter <CR>.

Commands are usually followed by a response that includes.”<CR><LF><response><CR><LF>”

Throughout this document, only the responses are presented, <CR><LF> are omitted intentionally.

The AT command set implemented by SIM300C is a combination of GSM07.05, GSM07.07 and ITU-T recommendation V.25ter and the AT commands developed by SIMCOM.

Note: Only enter AT command through serial port after SIM300C is power on and Unsolicited Result Code “RDY” is received from serial port. And if unsolicited result code”SCKS: 0” returned it indicates SIM card isn’t present.

All these AT commands can be split into three categories sy