Wifi calling no longer working on OnePlus 6

[_Rave_]

Hi

I purchased a Oneplus 6 from O2 a few months ago

After adding wifi calling to my O2 account, and then ensuring, 4G calling and Wifi calling were both enabled, I was able to use wifi calling just fine.

Then a couple of months ago, it stopped working.

4G calling and Wifi calling are still enabled

I've even tried setting Calling preference to Wifi preferred (when there is no 4G) but it keeps trying to connect using mobile.

It seems to have stopped working around the time of the last OnePlus operating system update, although  I can't be sure that was the cause.

Can anyone advise?

Thanks

[MI5]

I assume you have rebooted @_Rave_ ?

Mine is all working fine so must be something on your handset or account.

[_Rave_]

Hi

Thanks for replying. Its useful to know its working for someone.

It has not been working for several months. So yes, have restarted and powered off numours times since then

Do you have a OnePlus A6003 running on Oxygen 9.0.2?

Thanks

[MI5]

Yes I do.

[_Rave_]

Can anyone else help with why it might not be working?

[MI5]

Have you called customer service to check your account?

[_Rave_]

Hi

Sorry, I didn't see this reply. 

Quick question before I try customer service (I know that will take 20 mins+!)

If I turn off Mobile data, and under Calling preference, select Wifi preferred, will that test / force the phone to try using wifi, even if a mobile signal is available?

I had a suspicion the problem might be to do with our home network but I'm trying to prove / disprove this by testing on my parents wifi 

Thanks

[MI5]

Wifi preferred will force it onto wifi provided the wifi signal is capable of dealing with calls, regardless of any other settings, it will always override.