l Enable Wi-Fi calling: Turn on Wi-Fi calling.
After the setting is complete, select the contact you want to call and touch   to make a video call.
You can also touch   on the screen during a voice call to switch to a video call.
Use VoWi-Fi for a New Calling Experience
You can use VoWi-Fi to make voice and video calls in any location that has a Wi-Fi network, even
when there is no mobile network reception.
This feature must be supported by your carrier. Contact your carrier for more information,
including fees and charges.
Open  Dialer, go to   > Settings > Wi-Fi calling, enable Wi-Fi calling. Touch Mode and
follow the onscreen instructions to set the preferred network.
Dialing
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