have S3 TracFone that I'm trying to set up for AT&T

[AC Question]

My sister gave me her new TracFone Galaxy S3 (have TracFone emblem and everything). I put my at&t SIM in it to unlock it and the screen for the unlock code didnt appear. so i assumed it was already unlocked? put in several AT&T APNs and still nothing..

is it possible its not unlocked? or am i missing something...

thanks in advance

 

[Rukbat]

It's possible it has a Tracfone ROM in it. Check SamMobile Firmwares to see if there's a stock ROM for that model S3. If there is, see [Samsung] How to flash Stock ROM via ODIN for instructions on how to flash it to the phone. (Don't use an S3 ROM for a different model number - you could end up with an expensive paperweight.)