Ok, this is interesting. I got VoWiFi in Airplane mode on
OnePlus 5 running OOS 9.0.11. (I enabled VoWiFi via oneplus logkit)
These are the steps that I did for it to work, your mileage may vary,
1. Enable VoLTE, VoWiFi in sim settings and go to Homescreen
2. Enable Airplane mode from QS.
3. Go into sim settings and,
3a. Disable VoLTE and VoWiFi.
3b. Enable VoLTE and VoWiFi.
3c. Change "Calling Preference" from "Wi-Fi preferred" to "Mobile data preferred"
3d. Change "Calling Preference" from "Mobile data preferred" to "Wi-Fi preferred"
4. That's All.
In my current place, Jio signals drops very frequently while moving around the house. Hence, I have vowifi enabled.
I have a
Redmi phone with another Jio sim in a place where there's a better reception and using it as HotSpot (for WFH)
This OnePlus 5 is connected to the HotSpot.
Probably because its Jio network, I'm getting VoWiFi even on Airplane mode. I wish this isn't the case.