I think ur sim operator is not currently supporting wifi calling feature in ur smartphone. becoz wifi calling features automatically becomes visible if ur sim operator supports this service with ur handset. At present jio sim supporting wifi calling features in most of the volte enabled devices but in case of Airtel it is limited right now.
Wi-Fi calling facility in India is currently available with Airtel and Jio network providers.
You can drag down the notification panel to check the availability of this feature in your phone. This feature can also be found by following the “Phone app < Three dots < Settings < Wi-Fi calling”.
For this feature to work, your phone must be connected to a Wi-Fi network and have an Wi-Fi calling enable SIM card inserted.
You may also contact the above-mentioned network operators (Airtel and Jio) for further formalities to be performed in case the device supports the Wi-Fi calling facility.
Team Samsung Members