I'm about to travel to Taiwan and I'm going to bring my iPhone as my camera. Question is, is it possible for people to text me in the States using iMessage and WiFi? When I turned on Airplane mode and turned on WiFi, it said that airplane mode must be off. What do I have to enable/disable to get iMessage to work overseas without being hit with roaming charges. Can people still message me using a phone number if they're in the States?