Hi. I'm new to these devices and have a question regarding the 2 phone options. I come from the iphone. I have a factory unlocked iphone that I use a tmobile sim in. I ordered the nexus one with the plan today. My question is are these phones like iphones where the one through tmobile is locked to tmobile. In my situation att sucks. I would never use them and do not plan on switching carriers. And these phones won't work on any other carriers until the spring. So, I like tmobile and went that route. My iphone takes any sim so I can hopefully swap the tmobile one out. If I am wrong please let me know. Anyway, are the tmobile ones locked to them so popping in a att sim won't work or is the phone not locked and they just want the contract?