1. I am using a SIM808 module. It's working fine with normal MQTT over TCP, but does not work when trying secured MQTT.

  2. I sent 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.

  3. 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=1 command 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?

  • could you send me that firmware version (1418B05SIM808M32)? or could you tell me the site that you download it? Also, is there any newer firmware now?
    – prsbsvrn
    Nov 29, 2021 at 12:37

1 Answer 1


I updated the firmware version: 1418B05SIM808M32. Now all commands are working fine.

  • please send link of download firmware version: 1418B05SIM808M32 Dec 12, 2021 at 21:15

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