As a quiet guy myself, I’m betting that Skype is just not the best medium for reaching this guy. As much as he may love doing things with you, or hearing you share your thoughts and experiences with him, these Skype sessions are probably intensely uncomfortable. They’re going to make him even more self-conscious than usual and add an element of performance anxiety, like he’s got to cough up some meaningful converstaion now. That’s a real hard thing to do for guys like us.
My advice would be to keep your expectations low for these little sessions. Be prepared to do most of the talking, and when things get a little awkward, don’t make him feel like you’re anxiously waiting for him to deliver; find a gracious way to end the conversation without making him feel like he didn’t come through for you.
Believe me, for some of us, our lack of stuff to say doesn’t have anything to do with how we feel about our sweeties. “Opening up” may not be the right way of looking at it. He may not be holding back at all. Some guys inhabit a mental space that isn’t very verbal at all.