I am using the SIM800 series for some SMS applications. I need to check if an incoming SMS is new or old.
When I read the timestamp given by the AT+CMGL or AT+CMGR, the timestamp is the time when the SIM800 received the SMS, not when the sender has sent it.
Example: User sends an SMS, but the SIM800 is OFF Next day, I turn on the SIM800. SIM800 received the SMS, but the timestamp is new, and does not tell me that the SMS was sent yesterday.
Is there a way to read when the SMS was sent?