SIM900 / SIM800 USSD Code AT Commands – Working example
SIM900 and SIM800 GSM modules provide a set of commands to check the balance of the SIM card. Here they are, Before you dial a USSD code, you need to enable USSD commands and response notification using the command AT+CUSD=1. Once you enter AT+CUSD=1 and receive a OK string as response , your USSD command response notification will […]