Hi @dgilbert2, sorry to hear that you were having issues with your voicemail. Did you make any progress with this since you last posted or are you still stuck?
Cheers guys for jumping in to troubleshoot @Anonymous, @Cleoriff, @MI5, @Anonymous, @jonsie ! 
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@Marjo thanks for your post.
Unfortunately I am no further forward. I saw an O2 Guru in store on Saturday who re-checked my account and concluded that it was an Apple problem. Apple have come back and said its a O2 network / carrier settings issue.
So stuck between a rock and a hard place 
Any advice would be appreciated.
Well that sounds frustrating indeed @dgilbert2, let's check on our end just in case there's anything we can do to help - I'll drop you a PM here on the forum shortly to get a few additional details!
→ COVID-19 support - Help and support from O2 during the lockdown
→ Access for You: Registration - Find out how to register for our Access for You service.
→ Just joined the community or thinking of registering? Check out this handy starter guide!
→ Have a query about your account? See if the My O2 how-to guide will help
If you'd like to take part, why not register?
Re: iPhone XS Voicemail Issues
With many thanks to @Marjo my Voicmail problem has now been resolved.
I recieved a call from a very helpful technical expert who removed 4G and WiFi calling from my account. For some reason this upsets things but once removed my Voicemail was fully working.
4G and WiFi calling were then added back again to my account and Voicemail has continued to work.
Thanks again 
