Dial with prefix 0049 works, with +49 works not

Hello,

I live in Iceland, using an Icelandic phone number.

For a few day it is not possible anymore to dial "+49 xxxx" (Germany) - I get the message "Call failed" direct after dialling. Starting with "0049 xxxx" works as it should.

Strangely it happened suddenly Thursday last week.

Calling a number in e.g. France starting with "+33" works.

Another person in Germany told me that he has the same problem (calling a number beginning with +49 from the Contacts app).

Changing "Settings > Phone > Dial Assist" makes no difference.

Do you have any ideas why it si not possible anymore to dial with "+49"?

Using an iPhone 13 Max Pro, newest iOS.

Thanks

Claus