AT&T appears set to charge for FaceTime over 3G suggests a screenshot from iOS 6 Beta 3, reports 9to5Mac. Apple announced earlier this year that iOS 6 would allow FaceTime calls over the cellular network; however, carriers looking to gouge their customers can choose to charge extra for the feature.
We attempted to bring up the same same error message when enabling the FaceTime over Cellular feature on a Verizon iPad WiFi + Cellular, but the feature enabled without an issue. AT&T charges for a separate plan to use Personal Hotspot on its network, and the carrier appears set to replicate that process with FaceTime over Cellular.
AT&T provided the following official statement on the matter:
"We're working closely with Apple on the new developer build of iOS6 and we'll share more information with our customers as it becomes available."
To replicate the message in iOS 6 beta 3 you need to restore your network settings.