I'm a chick, but most of my friends are dudes... so I know how they think for the most part.
I'd say that next time you hang out, have a reason why you/he can't sleep over and go home. Do this 2 or 3 times and see if his calls become less frequent. If they do, you were just a f*** and that will never change. If they don't, he actually likes you so tell him how you feel.