Wait, did you buy the phone from Boost mobile and also activate a plan with Boost? I didn't think you could buy a phone from a carrier without a plan. If that's what you did, you will have to cancel your T-Mobile service and port your phone number to the Boost plan. If you bought the phone from Boost, and then canceled your Boost service and changed carriers, you would have had to have the phone unlocked before switching carrier SIMs.
If it's an old phone from Boost that you were saving as a backup, and now your primary phone broke, you would still have to have Boost unlock the device.
