N1b
Thank you for your reply.
It is not prepaid and it is not roaming.
It just not working entirely. No ability to call anything, not even 112.
I've just deleted it and reinstalled, nothing changed. Both sims are "unavailable". After some time with no action from my side 1 or 2 become active, but no ability to make calls or anything, calls are ending after 0,5s after the start or hang indefinitely without any error output. Then they unavailable again.