Wifi calling from my iphone15 pro Max is not working

Hello,

Would anyone be able to help as to why wi-fi calling doesn't seem to work on iphone 15 pro max

I have enabled the setting,via phone dialpad, settings, call setting, wif-fi calling.

But no symbol appears on the top of the screen.

I tried also via the quick shortcuts button,

I dont seem to get the notification pop up message,( your location-related information can be sent to google and your network operator in order to establish wi-fi calls) or the setting regarding if (wi-fi preferred or mobile preferred) when I enable my setting. that i've seen when I looked at YouTube on how to enable wi-fi calling. 

I have restarted the phone, the iOS is upto date.

regards

NandaR