HT1970: iOS: Updating your carrier settingsLearn about iOS: Updating your carrier settings
Currently Being ModeratedMar 8, 2013 6:26 PM (in response to isiduzit)
First thing to try is to reset your device. Press and hold the Home and Sleep buttons simultaneously ignoring the red slider should one appear until the Apple logo appears. Let go of the buttons and let the device restart. See if that fixes your problem.
If that doesn't help make an appointment at at Apple store and have your device looked at by a technician.