My uncle is going to Asia for 3 weeks. He will be travelling to Vietnam, Cambodia and Hong Kong. He has an ATT iphone 5. He wants to get sim cards that work in all 3 countries with DATA. Where can he get the SIMS? What company? Can he buy in states beforehand? Cost? Simplicity is best. Also, is there any way to turn his iphone 5 into a hotspot with these sim cards while he is travelling? My aunt wants to use her ipad also. Any help would be appreciated.