I have contacted TELUS several times to try to get VoLTE and WiFi calling working on my 6T running LineageOS 18.1. No luck.
I've never been able to talk to anyone who knows what I'm requesting.
VoLTE and WiFi calling settings are enabled on my phone but TELUS is not not allowing IMS registration.
One of these days I'll get around to trying the PDC method to spoof a Pixel 3.