So I tried to go on apple website and look for an unlocked version iPhone 6 Plus, but they only have T-Mobile version is without any contract, but it comes with a T-Mobile SIM card, does it means that I have to use this card and T-Mobile service? Can I use other carrier's card instead if I buy this version of iPhone? I travel a lot, like going back to China, I use China Mobile, can I use their SIM card on this T-Mobile iPhone?
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