SIM300 GSM/GPRS Serial Modem with RS232, TTL and Antenna
SIM300 is a GSM/GPRS Modem with RS232.
If you get "OK" status for commands like: "AT+CMGF=1" but errors like: '+CMS ERROR: SM BL not ready' for commands like: AT+CMGL="ALL", it just means that the SIM card is not inserted properly, though to the visible eyes it looks properly inserted. Just disconnect the power and try adjusting the SIM card slightly and connect the power and try once again to see if the issue is resolved. Also please be very gentle with the SIM card tray while inserting or removing the SIM card. Also don't tighten the screws of the antenna too much, just make sure it is connected properly without exerting too much force to tighen the antenna.
All modules are pretested before shipping. We recommend to use a 12V DC 2 Amps power supply and use a USB to RS232 to connect to the GSM/GPRS SIM300 module.
1 x SIM300 GSM/GPRS Serial Modem with RS232, TTL and Antenna