Last month reports in news were buzz that Airtel is planning to launch Vowifi in Decemeber & here it is working for most iphone users.
Atleast users in Delhi are reporting iphone 6s & above phone connecting to Vowifi from today aka 8th December 2019. Hopefully other phone users too get in very soon.
In Vowifi calls go thru via Wifi network instead of LTE which is VoLTE. It helps people in urban dense cities to get seamless voice connectivity via wifi when mobile signal is not enough to pass thru multiple concrete walls as most these place have inhouse wifi. For eg someone office in basement might not have good mobile network however wifi via fixedline is easily available. Now as one switch on wifi as internet changes from mobile data to wifi data similarly calling changes from VoLTE to Vowifi. Hence Vowifi solves all the indoor network problem for most as most cities nowadays have very cheap broadband/wifi connectivity.