T-Mobile, at least in the US, doesn't require contracts. You can get any of their phones on Flexpay Month to Month. That means you pay full price for the phone, get almost all of the same plan options that you'd get under contract, but you're not under contract, you're paying "month to month". As for being locked, after some period (3 months? 6? 9?) you can get your phone unlocked, as well. Assuming you don't find an unlockng service that can do it sooner.