I recently upgraded to the S21. it's a great phone but 2 numbers just won't ring out. 1 being my husband's and the other is my daugther ( both with virgin). I can text and do whatapp and messenger, video call etc but when I try to ring them ( the normal way) it's states that I have dialled an incorrect number. I've spoken to my phone provider and they don't know what the problem could be. All the other numbers I have no issues with.
So the 2 numbers you can't call are the 2 numbers you probably call the most. Perhaps you've accidentally blocked them? Can they call you? Do sms texts get through?