My boyfriend won't talk to me. Any advice?

My boyfriend doesn't seem to find any interest in anything that I say. I try to start a conversation but the only response that I get back is 'nothing'. If I ask him a question or for help, he will only say 'I don't know', 'yes', or 'no'. Whenever we actually start talking, he decides that he wants to go hang out with his friends or wants to go to sleep. We have been together for roughly 1 1/2 years and he enlisted in the military about a year ago. We talk fine in person and have no problems then, but he doesn't respond to me or say much at all to me on Skype or the phone. We text all the time, but if we are actually going to have a conversation, I have to start it. I am about to go to college on the coast opposite to him where my conversations to anyone will be limited to one 10 minute call per week and I have to sign out time to use my computer. What should I do? There are a lot of times where I do not see any progress in our relationship and it seems to go downhill sometimes. Whenever we have a night without conversation, he will send me a text saying that he loves me, no matter what and that he cannot bear the thought of losing me. Is there anything that we can do to make things right or at least better? Maybe some ways to get a conversation to last more than 2 minutes? We have argued about this multiple times and he 'never has anything to talk about'. It's really difficult for me to find things to talk about everyday and it frustrates me when he shows no effort at all. Please help me out. :/ I really don't want to lose him... We really have been through a lot of things together, having known him for nearly 5 years. He is very social towards his friends and family, but he has an issue talking to me I suppose. I tell him all the time that he can tell me anything because he knows that I am here to listen to him and I am very trustworthy. Thanks.