As per your concern kindly perform the following steps to set wi-fi calling on your device:
Enable Wi-Fi calling feature via Phone App: Phone > More > Settings > Wi-Fi Calling > Preffered SIM > Switch to activate Wi-Fi Calling.
Alternatively, you can also enable Wi-Fi Calling from the Quick settings panel. Swipe down from the top of the screen, and then tap the Wi-Fi Calling icon to turn it on.
Note:- If you can't see the Wi-Fi Calling options above on your phone, please contact your network provider to check that Wi-Fi Calling is available on your network and activated for your device. Make sure you are connected to a Wi-Fi network. If the network signal is weak or unstable, the Wi-Fi Calling feature may not work. To use Wi-Fi Calling, you need to insert an active SIM card from a carrier that supports this feature. Check with your network provider if your SIM card is supported. If that doesn't resolve the issue or if access to the feature isn't allowed, please contact your Network service provider for further assistance.
