How do you know...

If he wants you for just your body?
I've been having a thing with this guy for a while now (about a month)
We aren't dating but I'm really hoping we go further. We haven't had intercourse, but it feels as if he just wants to have sex and not a real relationship. 
He asks me to call eveynight; but it seems to always become dirty, I've been thinking of stopping that and seeing if he stays. 
What's some signs ladies??