1. Find "Wi-Fi Calling"
Slide two fingers downwards starting from the top of the screen.
Press the settings icon.
Press Mobile network.
Press the required SIM.
Press Wi-Fi Calling.
2. Turn Wi-Fi calling on or off
Press the indicator next to "Wi-Fi Calling" to turn the function on or off.
3. Return to the home screen
Press the Home key to return to the home screen.