Ignore the previous stupid comment. What you are experiencing is entirely normal, it's typical of a long distance relationship. The problem is that your relationship was based on a certain type of communication, and now that you have to use another form of communication, you have to kind of rebuild your relationship.

Think about it: did you really have so many more interesting things to say when you were in the same town? Probably not, and the problem is not the amount of things you have to say, but the development of a new pattern of communication that suits your needs.

The bottom line is that you need to persist, and find out how you can make it a more pleasant experience. With time you'll find out what you want from him, and what he wants from you on the phone. As an aside, many relationships have the same problem when they start on the phone or internet, and then move on to real life. People have plenty of things to say on the phone, but are silent face to face. The problem is the medium, not the relationship or the content.