thanks for your reply!
Yes, I'm aware of this method, but for that, the SMS-simcard needs to be active (primary), correct?
In my setup, my data sim card is primary to have a mobile data connection all the time.
(The data sim card has no ability to receive or send sms. it's a pure data sim card)
I don't think RUTx11 can react to SMS when the data sim card is primary.
I tested, but I had to make the SMS-card primary to receive SMS.
That's why I thought an option could be to switch sim cards depending on if a user is connected to the WiFi or not.
Looking forward to your reply!