When WiFi Calling is activated, you can make and receive voice calls over WLAN when you're in an area with poor or no network coverage. This service only works once you've received an SMS about Advanced Calling availability. Remember, you need to establish a connection to a WLAN.
Find "Wi-Fi Calling"
Slide two fingers down the display starting from the top edge of your mobile phone.
Press the settings icon.
Press Wi-Fi Calling.
Activate or deactivate WiFi Calling
Press Allow calls over Wi-Fi to activate or deactivate the function.
If you activate the function:
When WiFi Calling is active, the WiFi Calling icon is displayed.
Return to the Home screen
Press the home icon to end the session and return to the Home screen.