When Wi-Fi calling is turned on, you can make and answer calls using a Wi-Fi network when you're in an area with little or no network coverage. To turn on Wi-Fi calling, you need to establish a connection to a Wi-Fi network, select 4G (LTE) as network mode and follow the steps below. You can also visit the EE web page for more information about Wi-Fi calling.
Slide two fingers downwards starting from the top of the screen.
Press the settings icon.
Press SIM card & mobile data.
Press the required SIM.
Press WiFi Calling.
Press the indicator next to "WiFi Calling" to turn the function on or off.
Press the Home key to return to the home screen.