How can ii get an unlock code for a Samsung Behold for free?

I have a Samsung behold and tried to get it unlocked for free by calling T-Mobile. But mi brother ex-girlfriend had gav it 2 me but T-Mobile needs her social security number which ii dnt have. Is there any other way to get it unlocked for free?|||Call T-mobile back but don't tell them anything getting it from her. Tell them you purchased it at a yard sell. T-mobile is the only way to go to get it free, anyone else will charge you for it