I was not aware that a place existed in Cambo where Vietnam was supplying the power. That must be a complicated bill collection procedure.
I was wondering the other day why cell still works when power goes out, even planned power outages that affect almost the entire peninsula. As it turns out, cell towers have massive battery and generator backup that lasts 3-5 DAYS. According to one website I saw that if the power actually does go out for a cell tower it can be rather big problems for the company involved because rebooting is problematic and dropped calls means lost revenue. Basically it was more cost-effective for the company to ensure that these towers stay on no matter what.