If both people have internet, calling abroad can cost nothing. Apps route the call over data instead of the traditional phone network.
App-to-app: free
WhatsApp, Signal, FaceTime, Messenger and Telegram all place voice and video calls over the internet. As long as both ends have the same app and a connection, there is no per-minute charge — you only use data (or Wi-Fi).
Calling a real phone number
To ring someone who has no app, “VoIP-out” services like Skype or Google Voice let you dial a normal number for a small credit-based rate, usually still cheaper than operator international rates.
What to check first
Quality depends on the weaker connection of the two. On the move, Wi-Fi calling or a data plan with enough allowance keeps calls clear. For important calls, agree the app in advance so no one is left dialing the expensive way.
