Do you have a Tmobile account? If you have an account and meet the usage requirements they will issue you an unlock code.
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You'll need to make sure you meet all the requirements on our Unlock your mobile wireless device page. Since it's been so long, it's possible there may be a requirement that wasn't met. You may want to contact an Care specialist to look at your request and see what information they can find on it.
Manage your T-Mobile account