Does iOS 5.1 make my iPhone 4S 4G LTE capable?
If you upgraded your iPhone 4S to iOS 5.1 you may have noticed that the network indicator now shows "4G" instead of "3G." This is because Apple is now letting AT&T promote its HSPA+ (HSDPA) network as 4G. This does not mean your iPhone 4S is 4G LTE capable. Calling HSPA+ "4G" is a marketing ploy started by T-Mobile in 2010. AT&T is just doing the same thing.