Can some guys answer this please?

So I met this guy I really like (btw we r both 15) he lives 3 hours away from me and weve only seen eachother once but we txt 24/7 and we kno basically everything about eachother. I really want to talk on the phone with him tonight but I'm EXTREMELY nervous tht we r gonna run out of things to say and it will just be flat out akwardd. Any tips? Like wht if we have a akward silence (I DON'T WANT THT) how do I fill it? The only reason I'm asking is cuz I really like him and talking in the phone and txting r two totally different things cuz when u txt u have all the time in the world to think of wht ur going to say but on the phone its more quick paced. Sooo my question is any idea on wht to talk about with him? (not really sexual...) and if u have any questions tht could be used when playing 20 questions as well tht would be awesome :D thanks for the helpp!