What would your phone carrier ask if you want to block a number?

I have an AT%26amp;T phone I just wanted to know what would the phone carrier ask when you want to block a number. By the way would is cost money to block a number.|||They'll just ask for the number so they can block it. And maybe ask the reason why you want to. Just say they keep bothering you or something. I block people's numbers all the time and they do it for free with me