It had stock 4.0.4 -> could call. I've flashed FoxHound ROM -> after a while, when I try calling, it says "Not registered on network" . Tried GalaxSim, but everything looks ok. Restored back to ...
I was reading this answer and I need to comprehend this better: What is the technical difference between "selecting GSM" and "selecting WCDMA" in Network Mode settings menu? To save battery life, I'm ...