I had excellent results with 2D WiFi calling in Japan last year, but some research I've done (some could be dated) suggests that WiFi calling is blocked in Vietnam and some other countries.
I'm planning to buy a Viettel, Mobifone, Vinaphone or other SIM when I get there in December and use it in a Huawei E5783B 3G/4G wifi portable hotspot and use this for internet and WiFi calling.
Can anyone confirm this works in Vietnam, or is there a preferred provider that does support this?
