I'm in Korea right now, switched out my Verizon SIM from US for local SIM. As a result, I have a Korean tel number on my iPhone 5S. Question is: when I text message my contacts who are still in the States, who also use iPhones, am I drawing from the Data, or cellular allowance ( for SMS or MMS)? Because I would incur extra fees for making overseas calls or texts, and my contacts in the US would also if they reply to them. But with iMessaging, is it strictly off the data, so that these xtra fees wouldn't apply? I notice that for my contacts who have iPhones, I don't have to convert their number to the overseas dialing code, whereas those who have non-iOS devices and/or landlines, I do.