AT&T will most likely control and charge for the FaceTime over Cellular feature. The iOS 6 enhancement will move FaceTime beyond WiFi and let people use the service anywhere that they can get 3G service. Below is a statement that AT&T sent to 9to5Mac about the upcoming service:
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.
When 9to5Mac attempted to get the same error message when enabling the FaceTime over Cellular feature on the Verizon iPad WiFi + Cellular, the feature would work without an issue. AT&T charges for a Personal Hotspot plan and it appears that the company will attempt to replicate that process with FaceTime over Cellular.
Would you pay AT&T to use FaceTime over 3G? Let us know in the comments. Personally I plan to leave AT&T this month to switch to Virgin Mobile. How can you argue with $30 per month versus over $90 per month for a single line plan.