on 07-01-2020 11:42
on 08-01-2020 22:12
on 10-01-2020 13:32
on 10-01-2020 13:32
Odd. I have the exact same phone as you, also from O2, and the same software version but my WiFi calling is fine. Is the option also greyed-out in the Phone App (three-dots-menu settings)?
on 17-01-2020 23:44
on 20-01-2020 11:33