Have you considered that possibly he doesn’t have the best signal where he is? That maybe he, like @tranquilsea mentioned, is busy getting acquainted with this new place he’s in? I agree that he should call to let you know how he’s doing. But remember, you said he’s on a trip. So he may be busy enjoying his trip. Have you also considered that he may be waiting for your call, too? I mean, you could call once in a while, since, you know, the phone works both ways. It’s a two week trip, it’s not like he hasn’t communicated the entire two weeks. You probably also freaked him out, turned him off, and pissed him off by exploding at him. You need to learn to have a little something called patience and not try to pit things on him. If you were on vacation and wanted to enjoy yourself, would you be at your phone every waking moment, wanting to call your boyfriend? (well, if you’re a teenage girl, maybe that’s expected). You should apologize.
Also, I agree with @YARNLADY about asking “can he change?”. If you’re even going to ask that, then maybe you don’t need to be in a relationship with him. You can’t ever change someone, and if you’re in a good relationship and love that person for who he is, you wouldn’t want to change that person (unless of course he needs serious help, such as drug addiction, etc). But you can change circumstances. And one thing that needs to change is your apparent insecurity and your temper.
Edit: And trust me, I’ve had my fair share of freaking out over non communication during the summer. Whenever my one of my old boyfriends went to upstate NY, in the freaking mountains, a text that I would send on Monday wouldn’t be received til maybe Thursday (which was proven by the delivery symbol…thanks Verizon). Anywho, getting worked up and worrying and stressing over this and then flipping out is not the way to go, and is not worth it. This is the point where damage control may need to be done with a simple apology. Of course, it may or may not be accepted.