What's a perfectly reasonable explanation why a guy might take my number but decline to give me his?

You usually have to share a wall phone with about 6 other guys when you live in a halfway house. Maybe he doesn't want one of the other guys stealing you away from him, if you call when he's not home?

He's not going to text/call you, it's happened to me.

Oh and if he by chance contacts you, it's so he has control over the contact at first and doesn't want you hounding him.

Sorry for being harsh :/

The reasonable expanation is he wants to be in control. It could be he's just being polite and isn't interested.

He wants to to write this on a bathroom wall:

For a good time call (Your number).

He's going to ring you every night after you go to sleep until he really makes you Crazy Emm

He is married or wants to make sure you are not a head case first.

Either he has a girlfriend, or he doesn't have a phone. Whether either of those things is a problem for you is your call.

He must be married. He wants you as a side dish.

hes married

either has no intention of calling, he's already hooked up.. or u'll be a late nite drunk off his head booty call.. take ur pick..