Why can't I download iOS 7?
I have sprint and I was starting the download and it tells me that 6.3.1 is all that I can do.
If you have an iphone4 or above, you will just need to check back every once in a while or wait. IOS7 has been released, but everyone is trying to get it at the same time and it is overloading Apple's servers.
It has nothing to do with Sprint. It has everything to do with your phone. It physically cannot utilize the iOS7 software.
It only works for the iPhone 4 and up and it's not out yet.