Permanent voicemail notification

My FP2 permanently displays a notification saying I have a voicemail, but when I ring the number, it says that I don’t!

I realise this could be an issue with my network, rather than the phone itself, but I wasn’t having this problem on my previous phone (Samsung Galaxy III). For reference, I’m on O2, in the UK.

A post was merged into an existing topic: Cannot make voicemail notification disappear