I fixed someone's computer that I know. He doesn't really have much money, and gave me his Galaxy S4. I guess he didn't have enough money to pay the bill. I looked up the IMEI on T-Mobile's website and it says: "This device is being financed and has an outstanding balance that must be paid or it may not be able to be used on the T-Mobile network. " If I try to dial any number, it says not registered on network.
Is there a way I can unlock it so I can sell it? I already have a Galaxy S5 so I'm not interested in keeping this..