There is no “international” calling distinction when using the internet. FaceTime audio, Google Duo/allo/whatever, Skype/Teams, WeChat, and I’m sure there are plenty of other apps that let people communicate via audio.
WhatsApp is the main method of communication in some countries.
Where I live my most recent experiences interacting with businesses after a short phone call is switching to WhatsApp. "Do you have WhatsApp in this number?".
I'm not surprised that mangos can be ordered via WhatsApp. Like a friend of mine works in a purchasing department in company, and the last two cars the company bought were negotiated via WhatsApp.