I am using SIM900 GSM module connect to my AVR Microcontroller. I tested it with FT232 to see transmitting data. First Micro sends AT it will response OK
AT OK
AT+CMGF=1 OK
AT+CMGS="+9893XXXXXX" returns ERROR and doesn't show ">"
Could anybody advise me what to do?
Command AT+CSCS? will answer You what type of sms-encoding is used. Properly answer is "GSM", and if not, You should set it by command AT+CSCS="GSM".
And remember about "Ctrl+Z" (not "Enter") as a finish of sms text, please.