Can blocked callers still call through on iPhone?

I know it may seem like a silly question but for the iphone 4, I have just blocked a number by clicking "block contact" on the bottom of that screen. I was wondering can they still call through and it will just come up as " blocked" or if not can they put their number on private and then get through to me that way?

I don't want any contact, no calls, messages nothing

Nope they shouldn't be able to!