TT, I'm told that if you've been a customer in good standing for 90 days, T-Mobile will give you the unlock code for free. Contact them at 800-937-8997. If you need a reason you could always claim you are considering overseas travel, but from what I hear, they will give you one unlock code every 90 days anyway. You can also do it on the web at
https://my.t-mobile.com/ContactUs.aspx