To help determine whether this is your phone , network signal or your sim card at fault can you try your sim card in another phone.
And another sim card in your phone @Nikkiniks12
You can also run the diagnostic tool in your Samsung Members app.
A Samsung Service Centre can assess your phone if necessary.
If I can be of any further help then please don't hesitate. Take care. 😎
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. "