Currently Being ModeratedNov 26, 2012 10:05 AM (in response to mousehunter)
iPhone 4S only has 3G cellular capability. When 4G symbol is displayed on iPhone 4S screen it only has a fast 3G connection, which is misleading. The iPhone 5, when recieving LTE signal will display on screen LTE.
If you are having a connection issue with your iPhone 5, tap Settings App > General > Reset > Reset Network Settings. When done, in Settings App make sure Cellular Data is ON.