Sir Dancelot
Lurker
The instructions I've found for enabling wi-fi calling (on phones/carriers that have the feature) do not work on my dual-SIM OnePlus 6. This may be true for other phones with more than one SIM slot.
The way to enable/disable wi-fi calling is Settings -> Wi-Fi & internet -> SIM & network -> SIM 1 [or SIM 2]
and the Wi-Fi Calling settings will appear.
[ T-Mobile's T-Force found this for me after OnePlus told me to contact T-Mobile. The T-Mobile people found the answer on a OnePlus forum. (I looked there too but I guess my search skills weren't up to the task.) ]
The way to enable/disable wi-fi calling is Settings -> Wi-Fi & internet -> SIM & network -> SIM 1 [or SIM 2]
and the Wi-Fi Calling settings will appear.
[ T-Mobile's T-Force found this for me after OnePlus told me to contact T-Mobile. The T-Mobile people found the answer on a OnePlus forum. (I looked there too but I guess my search skills weren't up to the task.) ]