I have problems making WiFi Calls on my Samsung Galaxy Z Fold4
If you can't use WiFi Calling, there may be several causes of the problem.
Press the phone icon.
Press the menu icon.
Press Settings.
Press Wi-Fi Calling.
Press the indicator next to the required SIM to turn the function on or off.
Press the Home key to return to the home screen.
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Slide two fingers downwards starting from the top of the screen.
Press the settings icon.
Press Software update.
Press Download and install. If a new software version is available, it's displayed. Follow the instructions on the screen to update the phone software.
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Press the Side key.
Simultaneously, press and hold the lower part of the Volume key and keep them both pressed until your phone restarts.