Please perform the below mentioned steps to resolve the issue:
From home, swipe up to access Apps. Tap Setting > Wi‑Fi Calling. – or – Pull down the status bar to display the quick settings menu and tap. Wi-Fi Calling. Tap On/Off to turn Wi-Fi Calling on or off.
For further assistance, register your concern in Samsung Members Application (Open Samsung Members Application > Get help > Send Feedback > Error report/Ask questions).
