What should I do???Nothing to talk about?HELP?

ME and this guy have just started dating.On June 8th exactly.I wont see him much cuz of summer vacation.Hes going to visit his mom all Summer.So we always talk on the phone.And I don't know why but I feel like we have nothing tot talk about.And Although hes very sweet and expressive with me I'm not the same way.I REALLY do like him its just I cant really express myself the way he does.Any advice?Please help :(