As a process of elimination can you try your sim card in another phone and then see what happens @SallyVB
This may not be your phone but instead be network connection based.
Have you spoken with your network ?
I wish you all the best with this issue.
Daily Driver > Samsung Galaxy s²³ Ultra 512Gb in Phantom Black.
The advice I offer is my own and does not represent Samsung’s position.
I'm here to help. " This is the way. "