I am not sure if vodafone / Vi had wifi calling before (on Android may be?) but I don't think it was present on iPhone. But with iOS 14.5, I can now enable wifi calling on my iPhone. I even got message from Vi to upgrade to this iOS and enable WiFi calling.
Operator shows "Vi VoWiFi" when wifi calling is enabled and one is connected to wifi.
Operator shows "Vi VoWiFi" when wifi calling is enabled and one is connected to wifi.