Some guys (like some girls) are just not chatty. It might be that they're kind of shy. So, don't take it personally if you're having a hard time getting him to say more than "yeah" or "uh-huh" on the phone. It doesn't necessarily mean he doesn't want to talk to you.
There are a couple of things you can do to try and get him talking. One is the previous tip -- finding out what he's into, and asking about it. Another good idea is to ask him open-ended questions. If you keep asking him things that only require a yes-or-no answer, a yes or a no is all you're likely to get. Instead, put your English class skills to good use and ask questions that require more thorough answers. For example, instead of asking, "Do you like the new Bruno Mars album?" try saying "What do you think of the new Bruno Mars album?" That will help get him talking, and hopefully he'll feel a bit more comfortable.