My iphone can't be carrier unlocked?

I buyed a iphone 4s off someone and it is carrier locked with tmobile. I want to fully unlock it. I have got the imei number and also the box. I contacted tmobile and also submitted to do it online on their website but they never replied. Anyone know how I can unlock it and how much it may cost?

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You can take it to the Apple Store to get it unlocked.

If you are not a customer with T-Mobile they will NOT unlock the phone for you. So not being a customer, you will need to PAY a cell phone unlocking service, to unlock the phone, either a local company (where you live), or one off the internet. Me I would pick a local shop, where I can get it done while I wait.

If you are a customer of T-Mobile, you call customer service and ask for Tech Support and ask for the subsidy unlock for your phone. If they ask why, you say, you would like to be able to use local SIM cards when traveling outside the US.