Cannot turn on wifi calling with iPhone dual SIM (eSim)

[lxpollitt]

My O2 says that 4G & Wifi calling is enabled. But when I try to enable it in my iphone settings the phone pops up a dialog saying I have to enable it on O2 first, even though it is already enabled on O2 and has been for weeks.

I'm using an iPhone 11 Pro Max on the latest iOS release.  My O2 account is using an eSim.

I cannot call O2 support because I have no cellulary reception where I am.  I cannot leave where I am because I am under a 2 week covid quarantine. 

I really need to get my calls working, so any help is greatly appreciated.

[MI5]

@lxpollitt 

If you have wifi you can use Skype to call O2 Guide: Coronavirus Community Help and Support 

but I'm not sure if wifi calling works on esim or not?

[lxpollitt]

It worked for me during my last stay in the UK (over the summer). It looked like it turned off when I was outside of the UK, and now won't turn back on again.  But if could be coincidence and unrelated to travel.

If no one on here has ideas then I'll definitely try Skype calling. Thanks very much for that suggestion.

[MI5]

@lxpollitt 

You're welcome and check that your data apn is set to iData as that is required for wifi calling on iPhone too.

[lxpollitt]

Thanks for the iData suggestion. I checked and all the cellular data options I see have the APN set to idata.o2.co.uk.

There's no settings in the LTE section, though that is marked as optional in the iPhone settings. So I just tried adding the APN details to the LTE settings. It didn't seem to make a difference, so I deleted them again.

This did remind me that in addition to wifi calling, I also can't switch on the 4G VoLTE calling option, even though My O2 says it is enabled on my account and iPhone 11 Pro Max supports it.

[lxpollitt]

If no one has other ideas then I'll try connecting to O2 support via Skype as suggested.

[MI5]

@lxpollitt 

Does your visual voicemail work or do you have to dial 901 to listen to voicemail?

iData may not be active on your account if that is the case.

[lxpollitt]

Visual voicemail appears to be working.

[MI5 · Accepted solution]

@lxpollitt 

OK, that confirms to are set up for iData......

Give them a call as above to check everything.

[lxpollitt]

O2 support were able to resolve the issue by reseting wifi calling on my account (turned it off and on again). Thanks for the help.