What is the best app for making free phone calls while traveling abroad?

The question for making ‘free phone calls’ I will take to mean calling:

1. A local PSTN number in the country;
2. Making an international call to a fixed phone/mobile phone somewhere in the world;
3. It does not mean making an ap to ap call (peer to peer call.. eg using Whatsap to call another Whatsp user);
4. We are really saying ‘ap to call a PSTN’ terminated calls.

For the best through put you are probably looking at Skype. Quality is good on WhatsAp. Best calls today are ap to ap calls. At Future.Travel we have a fixed PSTN number, and also list direct calls via WhatsAp, Viber, Skype, and Zalo for contacting us. Serious business requires the ability for global customers to call you 24/7 without the limitations of phone (PSTN) restrictions or tolls.