I want solution. i cant call anyone with my iphone ! i can do anything without calling, send message or anything.

I had an iphone and it was broken, i mean, it had a problem with its network. Also, it stick up with itunes. it seem unflexible.. And then this problems, apple send me a new iphone (5). but now, i cant call anyone ! I can send message, i can do everthing without calling ! What Apple is going to do now ? I thougt Apple is reliable but i have same problem again ! I hope apple can see this message. I wanna fix this problem. but i dont trust iphone 5 anymore...