Add unicode support in 2G gateway?

Do we support Unicode text message? when I received a Unicode message, it just got ??? in the mqtt channel. Is there anyway I can get or decode the message?

I don’t think A6lib support unicode (the library used for SMS by OpenMQTTGateway).
I suggest you to ask on the library repository this support or to submit a pull request if you have the competencies.
Here is some documentation: