Wi-Fi Calling, commonly known as Voice over Wi-Fi or VoWiFi, is a feature that comes standard on most modern smartphones. Wi-Fi Calling allows you to make and receive voice, text, and video calls using a Wi-Fi network instead of a cellular network. This is considered one of the advanced features of smartphones worldwide.
It could be very disappointing for the Xiaomi Mi A2 Lite user’s that the WiFi Calling function (VoWifi) has not been enabled on this phone, along with the Volte. You could allow VoLTE by dialing *#*#86583#*#*, but there is no such way to enable WiFi calling on this phone.