I'm in the Middle East every month for about 10 days at a time on business. I have an unlocked phone that I bought (all international ones are unlocked). I used to have a T-Mobile phone, and in the Settings menu one could click a check box that said "enable WiFi calling" and it worked just like a regular phone.
That box is not present in the software. I have tried Talkatone, Viber, and others but I don't think they work in this part of the world so that I can get texts, nor answer calls (it doesn't ring here when somebody calls).
Can anyone help? Very frustrating.