Consumers have been able to make calls over WiFi networks for quite a while now, but now Vi users in Maharashtra and Goa, Gujarat, Delhi, Mumbai, and Kolkata, who have a 4G activated SIM card, can access their contacts over Wi-Fi calling.
How to enable Wi-Fi calling: All iPhones – 6s or above
Settings > Phone > WiFi-calling
About Wi-Fi Calling
Get seamless and extended Indoor coverage – Make calls anywhere as long as your have WiFi connectivity!