Owners of T-Mobile Samsung phones are having a field day after discovering a glitch،
Carriers have a simple and understandable reason for locking phones. If they let you get a phone at a discounted price, they want you to stay with them for a predetermined period of time. That doesn't make carrier locks any less annoying.
Some Samsung users have discovered that their phones can be unlocked easily, even if the devices have not been refunded. All you have to do is go to the Settings app, tap Connections, go to More connection settings, and then open Network Unlock. After that, you need to request temporary unlock, and after a short wait, tap Permanent unlock, and ta-da, your phone will be unlocked.
After all, consumers have been able to unlock their phones themselves since at least August. It therefore seems unlikely that TMobile is not aware of this deficiency. That said, while this seems intentional, since there is no official confirmation, you should take this route at your own risk.
One theory floating around is that Samsung's One UI software has a bug that automatically approves unlocking if a device is turned on. TMobile.