AT&T has had periodic network issues throughout the U.S. at various times over the last three years. What you're describing sounds like it could have been one of those.
I also experienced this problem for about 2 weeks, earlier this year. It resolved on its own, without me having to call anyone at ST.
I agree that this is happening. My point is that the problems are not deliberate limits imposed by ST, but rather, technical failures related either to the device, the user, or the underlying network.