How to remove network lock samsung galaxy s advance

Title says it all. I have been scouting the net for the past day and a half and haven't found a way to remove/unlock the network lock on my SGS Advance. It is already rooted. I have tried those SGS unlocking apps, and didnt work. Does anyone know how to unlock a Samsung galaxy advance without purchasing/paying for unlocking service? ps i have also tried the instructions from this page thread, http://forum.xda-developers.com/showthread.php?t=761045 . but when i checked, the nv_data.bin in my phone contained nothing (0 bytes)