Samsung Galaxy S6 Edge - How to enable WiFi calling
The Samsung Galaxy S6 Edge allows you to make voice calls over Wi-Fi networks thanks to the Wi-Fi calling feature (given that this feature is supported by your mobile operator).
To enable this feature:
Tap on Apps > Settings > More connection settings
Toggle Wi-Fi Calling On.
Several preferences are available, Wi-Fi Preferred, Cellular Network Preferred and Never use Cellular Network.