Geting calls from disconnected Number?

Eversince i stopped allowing private calls to my phone from this guy, somebody has been calling me from a landline disconnected number. How is that possibe? How can they call you when the phone is so called disconnected? They called me 3 times already.

I think its this guy that used to call me private all the time. His girl and son live with him. Are there some type of phone tricks you can use these days, to keep somebody from geting your number, or calling you back.
Additional Details
They always let the phone ring about 3 times, then i will pick up up. I will say hello about 2 times, but nobody says anything. I hear them breathing and i hear the tv lowly in the background. It seems like somebody is just calling to hear my voice and thats it. Gosh, People are idiots. Some guys need to grow balls.

Its a local number too. Not from out of state anyway. I try to call back, but it says...this number has been disconnected or no longer in service.