@Ehartwork My point is, you are probably not testing VoWiFi at all, since that has not been reported to work on this device by regular users. One developer claims to have gotten it to work on a FP5, but this has not been independently verified.
The fact that what you think is WiFi calling doesn't work when there is no cellular service is a strong indication that WiFi calling is not available on this device.
. I just chime in when I see a question I think I can answer. Otherwise, I leave all well enough alone 