I'm not sure why the GP said his iPhone 4 won't upgrade past iOS 5, but it's worth noting: while an iPhone 4 can be upgraded to iOS 7, actually doing so is a bad idea unless you want your phone to run slow as molasses. You'll be much better off on iOS 6 or 5.

(I suppose there may be a security argument for upgrading as far as possible, but it's not like iOS 7 is up-to-date either. If you're concerned about security, you shouldn't be using an iPhone 4.)