HT4972: iOS 4: Updating your device to iOS 5 or laterLearn about iOS 4: Updating your device to iOS 5 or later
Currently Being ModeratedJun 20, 2012 2:22 PM (in response to JHB456)
You have a runaway background process that is sending data or trying to send and failing, over and over. Try a reset (hold HOME and SLEEP until an Apple logo appears. If that doesn't resolve ittry running the battery all the way down until the phone shuts off, then charge for 4 hours with a wall charger.
Other steps include turning off or deleting any Microsoft Exchange email accounts, rebooting, and turning them back on (or adding back).
Beyond that you have to try to identify the app. Any app that uses data in background is a suspect, but Facebook seems to be a common problem.