ERROR response to +CMGS command

Syntax for +CMGS varies depending on if the modem is in text mode or PDU mode. Use the +CMGF? command to check which mode the modem is currently in.If +CMGF=0 (PDU mode) syntax for +CMGS is AT+CMGS=If +CMGF=1 (Text mode) syntax for +CMGS is AT+CMGS=Consult AT Command manual for further details.