How to unlock it for another country sim cards?
You need to be a Tmobile customer and meet the requirements in the link above.
If you are not a T-Mobile customer, you could take it to one of those unlocking kiosks in your local shopping center or use one of the many online unlocking services to SIM unlock the device.
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Manage your T-Mobile account
Use the T-Mobile App or your My T-Mobile account
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