>"the wifi is slow”, AT&T will shift to data and they will detect it’s an international call and bill you as if it’s a regular international cell call. There i

>"the wifi is slow”, AT&T will shift to data and they will detect it’s an international call and bill you as if it’s a regular international cell call. There is an option in iOS called 'Wi-Fi Assist' (Settings > Cellular > (Scroll to the bottom) > Wi-Fi Assist). It will, "automatically use cellular data when Wi-Fi connectivity is poor." Make sure that's disabled. It should also show you how much you've used (mine is showing 522MB).