Originally Posted by StLBluesFan
How about neither? I expect AT&T is simply holding back for a bit on allowing that functionality for bandwidth reasons. Just as they did with other potential bandwidth suckers like tethering and MMS. It will be enabled eventually, though I'm hoping Facetime via 3g isn't degraded too badly.
Your typical voice call (with compression) is about 8kps.
Your typical video call (with compression) is about 512kps, or about 64 times that of a voice call.
AT&T has twice as many smartphones as its nearest competitor. I'm sure this is the reason why they don't want to open it up quite just yet. T-Mobile has far fewer customers, far fewer smartphones.
On the side, if you want to quickly burn up your monthly data allocation, just make a few quick video calls.