First, if anything like this has been posted already, I am sorry... But I am hoping to get help for my specific situation. Okay, I work for a small company and only three employees have company iPhones. The other company phones are just standard phones, so we will just pick up free phones for them. Each one is a Sprint 16 GB iPhone 4S. We are looking to potentially switch to using T-Mobile (or AT&T, but most likely will be T-Mobile) as our Cellular Provider. I have no control over when this happens or anything along those lines. I have Jailbroken my personal phone a couple times, so I am familiar with that process. I have one job: Figure out a way to make the iPhone's work for T-Mobile or AT&T. I do not know what the contract situation is, and what my boss plans to do there. I just need to understand "unlocking" the phone. SO.... - What is the different between Factory Unlocked and User Unlocked? - Does Sprint even other that service? (I know AT&T does when you are out of contract) - How is a User unlock accomplished? - Is it currently possible on the iPhone 4S? I am pretty sure all of them have iOS 5.1.1 currently. If you do not want to type it all out: Please feel free to post links to other threads or pages that you think explain it well. Thanks in advance. Edit: AT&T now, Passing on T-Mobile.