Just announced over at AT&T! "When FaceTime over Cellular launched in September 2012, we explained that we wanted to roll it out gradually to ensure the service had minimal impact on the mobile experience for all of our customers.
As a result of ongoing testing, we're announcing AT&T will enable FaceTime over Cellular at no extra charge for customers with any tiered data plan using a compatible iOS device.
This means iPhone 4S customers with tiered plans will be able to make FaceTime calls over the AT&T cellular network. AT&T previously made FaceTime over Cellular available to customers with a Mobile Share plan and those with an LTE device on tiered plans.
Of course, FaceTime over Wi-Fi remains available for all customers who have a compatible iPhone or iPad.
We have already begun updating our systems and processes and expect to start rolling the update out to customers on an ongoing basis beginning in the next couple of weeks. Customers do not need to do anything-the update will be applied automatically over the next few months.
Only AT&T offers benefits like the ability to talk and surf at the same time, the fastest download speeds using AT&T 4G LTE, and a variety of flexible plan options to meet customers' needs."