All the carriers are retarded. What is the point of selling an unlimited data plan with limits on it. That's complete false advertisement. They are in for one gigantic lawsuit. You can run up the same (actually more) usage by streaming youtube and music. Streaming is not tethering and it consumes more data than tethering (unless you are streaming video and music while tethered of course). There is no way they can tell whether you are tethering by bytes used per month alone.