"To enable FaceTime over cellular on this account, contact AT&T at 611," reads the prompt in iOS 6, discovered by iDownloadBlog. The message first appeared with this week's release of iOS 6 beta 3, and only shows up when a user attempts to enable FaceTime over 3G on AT&T's network, not Verizon's.
For its part, AT&T refused to elaborate further on the error message found in the third beta of iOS 6. In a statement, the company said it is "working closely with Apple on the new developer build," and that it will "share more information with our customers as it becomes available."
The error message in iOS 6 is similar to the type of prompt users receive when they attempt to turn on the "Personal Hotspot" tethering feature already found in existing releases of iOS. That's led some to assume that carriers like AT&T are at the very least considering charging users for the ability to make FaceTime video calls over 3G.
FaceTime over 3G is one new feature coming when iOS 6 launches this fall, though the functionality will be restricted to the iPhone 4S and cellular-capable models of the third-generation iPad.
Update: One AppleInsider reader inquired with U.K. carrier O2 about support for FaceTime over 3G. An online representative indicated that the feature will be included in the data allowance for iPhone users (see screenshot below).
When FaceTime was first announced with the launch of the iPhone 4 in 2010, then-Apple Chief Executive Steve Jobs indicated that his company wanted to allow FaceTime calls over 3G, but that Apple needed to "work a little bit with the cellular providers" to bring that capability to users.
Apple already allows some carriers to block or restrict certain functionality on their networks. For example, when iOS 3.0 was released with tethering capabilities, AT&T blocked the paid feature until a year later, with the release of iOS 4.0.