T Mobile Device Unlock App. What we do now is process the unlock code and email it to you. I googled and this is how other people with similar problem got it. The app will uninstall itself after a permanent unlock.
If you insert an unaccepted simcard in this type of device, the unlock request will be shown in this special app. The features of this app include the ability to remotely request mobile device unlock.
Sir yours is a good question too.
The device must be paid in full. May require a device restart for changes to take affect. Unlocking iphone is not done via an unlock code, but the device is remotely unlocked on apple service instead. That's how the device unlock app will get the right.