I got the iPhone 4S this morning in-store from Sprint. I tried putting in an AT&T prepaid micro-sim to see what would happen. The iPhone attempted to activate the SIM after stating activation was required, then said it could not activate because it was not a supported carrier for that particular iPhone. So that is a bummer. This doesn't seem to correlate well with Sprint's statement, unless they were only talking about Sprint phones purchased online or through a 3rd party retail store rather than directly through a Sprint Store. If anyone else can try this out with the same or a different carrier micro-sim that would be great. Thanks. Any feedback? Am I doing something wrong here?