Dies this happen everywhere or in a particular place @stookie
Most networks have a mast status Checker to be able to check local and surrounding masts.
If your sim card works OK in another phone then do please seek support from a Samsung Experience Store or Samsung Service Centre.
I wish you all the best with this.
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. "
