Enhanced Caller ID with AT&T Call Protect Plus

I’m now subscribed for the Call Protect Plus. I wanted to see the caller name of people who are unknown. But when a person not saved in my contacts calls I still don’t see caller name. How does this work? Am I confused and it’s actually people who block there number that you see there name? And if so why can’t I see caller name of the non blocked numbers that call which are not in my contacts? Someone please help.