I made another try earlier.
Now “unknown ring” has been logged and received a push message. So far so good.
Then I activated the permanent mode and tested again, here the permanent mode (ring to open) was logged, but no loggin about “unknown ring”. This made me realize that “unkown ring” is only logged if no ring to open, respectively no permanent mode is active. Can anyone confirm this?
If so, that would be a great pity. This function in particular would be useful. (Parcel services etc.)