I have a normal phone right now and I will be upgrading to the iPhone 4S/5 when it comes out. I know it's necessary to get data on ATT but if I get the 250 mb plan, (I have internet at work, school and home so it's unnecessary to get 2 gb.) will it let me know before I go over? Or will it automatically stop when I hit my 250? I just don't want to get hit with those stupid crazy high overage data fees. Also, presuming that the iPhone can be unlocked, can I use it in Australia, Taiwan, and Europe? (I travel a lot but I've never had a phone out of the States.) Also, I can use iMessage internationally without getting hit with roaming if I'm on O2 or Rogers since it's using Wi-Fi right? But my number might be different if I'm on a different carrier right? Or is it messaging me by my iTunes log in? Thanks!