The Verge confirms in its testing with a review unit of the new iPad with 4G LTE that FaceTime video calling remains limited to Wi-Fi networks despite the fact that LTE offers greater bandwidth than many Wi-Fi networks.
We've just confirmed that although the new iPad has incredibly fast download and upload speeds over LTE, FaceTime video chat still won't work directly on the 4G network. As you can see in the positively vexing screenshot above, attempting to initiate a FaceTime call over LTE fails out with a message exhorting you to connect to a Wi-Fi network.
As the report notes, Steve Jobs claimed during FaceTime's introduction at the iPhone 4 media event in June 2010 that Apple still needed to work with carriers to support FaceTime over cellular data networks and that the feature would consequently remain Wi-Fi-only at least through 2010. Well into 2012 and with 3G now giving way to LTE on the new iPad, it seems that carriers are still unwilling to allow FaceTime calls to be transmitted natively over their networks, presumably due to concerns about increased data usage and strained network capacity.
Article Link: FaceTime Video Calls Still Limited to Wi-Fi as LTE iPad Rolls Out