I am using a SIM808 module. It's working fine with normal MQTT over TCP, but does not work when trying secured MQTT.
AT+SSLSETROOT="C:\USER\HENRY_SSL.CRT"to set the root certificate (see this document: "SIM800 Series_MQTT_Application Note_V1.03"). The response I'm getting from the GSM is:
+CME ERROR: unknown.
When I try
AT+SMSSL=1, I get the same error. I checked with HTTP commands and it's working fine, but the
AT+HTTPSSL=1command does not work. The SIM808 does not respond to SSL related commands.
But as per the Simcom website, the SIM808 does support SSL. Do I need to upgrade any firmware?