Airtel VoWiFi not working on iPhone 12 (even though connected to WiFi)

Hi! I was curious if Airtel VoWiFi works on your iPhone. I use two SIMs on my iPhone, one of them is Jio and the other one is Airtel. What i have noticed is that the voice calls from Jio number are significantly more crisp, clear and sharp compared to the voice calls made from the Airtel number. No matter which location or WiFi network i am connected to, Jio always shows Jio WiFi but Airtel sometime shows and sometimes doesn't show Airtel WiFi. I just wanted to know if this is the case with all iPhone 12 users or is this some problem unique to my device. Thanks in advance!