As summer approaches and some may be thinking or planning overseas trips, if you are an AT&T mobile customer, I have good news for you. AT&T has added free international WiFi calling. It does require that you have an iPhone 6 or newer. And you need to turn the option on in Settings. To do so launch Settings. Scroll down to Phone and Select Wi-Fi Calling.
Alternatively, when overseas, you can use FaceTime, Skype or WhatsApp to make free calls over WiFi.