What is and how do i find a network code to unlock samsung highlight t749?

[all16eyezonme]

got a new service but jus bought a samsung highlight bout 4 months ago and dont wanna really buy a new phone for AT&T so what exactly is and how do i find a network code to unlock the highlight
i didnt know i was goin to get new service my dad surprised me with it

 

[froggy_logic]

why did you "jus bought a new phone 4 months ago" when you knew you were going to get a new service?? not very forward thinking of you