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We are using the SIM868E module for connection via GSM, with internal communication over UART.

We need the SIM868E module to communicate with an HTTPS server, (using SSL), however after sending the commands AT+HTTPSSL=?, AT+HTTPSSL=1 or AT+CIPSSL=? the SIM868E module responds:

+CME Error: unknown

(with CMEE level 2).

The specs note that SSL/TLS are supported by this module: (https://simcom.ee/modules/gsm-gprs-gnss/sim868e/).

The firmware on the chip (requested using AT+CGMR) is Revision:1418B02SIM868E32_BLE_EAT.

How can we fix this problem?

Roberto Caboni
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Michiel van Lohuijzen
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  • If you get that error even with test command `AT+HTTPSSL=?` it could be that that xommand is not supported at all in your product variant. As a further check, try issuing `AT+CLAC` (the list of supported commands) and see if `AT+HTTPSSL` is present. – Roberto Caboni Jul 08 '20 at 19:15
  • Thank you for your response. AT+CLAC seems to be unavailable too. Would it be possible to use newer firmware from a different, but similar simcom module? – Michiel van Lohuijzen Jul 09 '20 at 07:41
  • I am not sure about it. Probably not. Just a question: did you issue `AT+HTTPINIT` and `AT+HTTPPARA` (as recommended by the SSL user guide) before `AT+HTTPSSL`. – Roberto Caboni Jul 09 '20 at 10:10
  • Yes. I did as in the application notes. I fear I have to find another way to secure my data. – Michiel van Lohuijzen Jul 13 '20 at 07:51
  • I've built an answer containing all the info I could find (even though they are not good news). – Roberto Caboni Jul 14 '20 at 09:35

1 Answers1

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According to 2019 SIMCom products catalogue it seems that for SIM868E device there's not support for TLS feature (TLS is the standard name for the SSL protocol).

Just in case the link becomes unreachable, I attach a screenshot of the relevant page of the document:

enter image description here

as you can see, TLS dot is "empty".

Nevertheless, I have to say that SIMCom documents are sometimes contradictory and confusing: in fact in the SIM868E flier claims that the SSL SW feature is supported, but in the SIM800 series AT command manual there's no mention of SSL AT commands.

I will update in case I find any new piece of information about it.

I would honestly avoid trying strange things like flashing the SW of another module. It would be like searching for trouble. And in your case you would lose your positioning capabilities (GPS/GNSS).

Talking about your issue in particular, you'll probably have to compile an SSL library on your host processor (for SSL handshake and data encryption) using the TCP/HTTP commands of your device to transport data to the server. It's not a simple job.

Roberto Caboni
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