I have a data only sim which has poor signal at home. Every time my phone loses signal and gets signal again it displays this message.
Möglicherweise fallen vom Netzbetreiber SMS-Gebühren beim Aktivieren von FaceTime und iMessage an.
which translates to
Your operator may incur SMS charges when you enable FaceTime and iMessage.
If I leave my phone for a long time it connects to the network maybe 30 times then I have 30 alerts to dismiss before I can use my phone.
I really don’t want to change my number as I’m only using a data only sim while in another country.