Check that the phone is eligible for unlocking
Make sure the device is fully paid off
Make sure the account is in good standing
Ensure the phone has been active on T-Mobile for the required period
Connect the phone to Wi-Fi or cellular data
Open the T-Mobile app or contact T-Mobile support
Request an unlock for the device
Follow any on-screen instructions or confirmation steps
Restart the phone after the unlock is approved
Insert a SIM card from another carrier to verify the unlock