Carrier will not block it for you. You need a phone that has that option/app to do it. Or you can use a proxy number such a google voice and do it yourself.
Not true, Verizon blocks #s for you through your login thingy online or you can call customer service and they can do it. I'm sure AT&T does it too.
I have AT&T also and looked into this pretty recently. If I remember correctly, they offer a service for $5 a month (I think) and give you a handful of numbers to block. Seems like a ripoff if you ask me.
Verizon must have added this recently because I called them a couple years ago to have a number blocked and was told they couldn't do it.
Yep, it's some kinda parental control thing. I had to get it like a year ago for a crazy ex-gf. Blocks texts, voicemails, anything. If you ask they will give you a free trial of it, for a month or 3, can't remember. If your phone has the option you can just send the calls directly to voicemail, I know android phones do.
Go here to read about it. http://www.wireless.att.com/learn/articles-resources/parental-controls/smart-limits.jsp If you have a smart phone, then theres an app for that.