WiFi calling incompatible with voicemail.

[UkSparky]

Hi,
Apologies if this has been covered elsewhere but have searched to no avail.

Long story short I migrated a PAYG number onto my contract sim a couple of days ago.

All has gone to plan except for the fact that voicemail refused to activate on the contract sim.

I tried various methods to get it to work, to no avail. All I was getting was "we cannot turn i
on your voicemail as we don't have your number."

After a long time on the support chat going round in circles I called retentions who looked into the matter further. It transpires that the reason my voicemail wouldn't activate was that I had WiFi calling enabled on my account. They duly disabled it and hey presto my voicemail is working correctly.

They informed me the two are incompatible, which leads me to ask why?

I don't want to enable WiFi calling on my account again in case it messes up voicemail. One other thing I've noticed is that my diverts aren't going to the usual +447802091901 number, but I'm leaving it alone as it now works fine.

Thoughts please?

[Cleoriff]

@UkSparky 

What phone have you got? There used to be a problem with some Sony phones last year with Voicemail and Wifi calling but thats fixed now.

I do know O2 are updated Voicemail, so not sure if that's the problem?

https://www.o2.co.uk/connectivity/wifi-and-4g-calling 

[UkSparky]

Thanks for your reply.
I have an unbranded Nokia 3.1. WiFi calling was working fine on the contract sim up until the number migration.

Ah well, I'll just have to leave it turned off as voicemail is more important to me.

[MI5]

@UkSparky 

More likely just the usual needing to wait a while whilst all O2 systems update.