我们使用 SIM868E 模块通过 GSM 进行连接，通过 UART 进行内部通信。
我们需要 SIM868E 模块与 HTTPS 服务器通信（使用 SSL），但是在发送命令后AT+HTTPSSL=?，AT+HTTPSSL=1或者AT+CIPSSL=?SIM868E 模块响应：
+CME Error: unknown
（与 CMEE 2 级）。
规格说明此模块支持 SSL/TLS：（https://simcom.ee/modules/gsm-gprs-gnss/sim868e/）。
芯片上的固件（使用 AT+CGMR 请求）是Revision:1418B02SIM868E32_BLE_EAT。
我们如何解决这个问题？
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:
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.