Voicemails appearing on multiple devices

[etherp]

We have 3 iPhones in the house on the same O2 account.  Different phone numbers obviously.

Over the last few months, call logs have started mirroring across the devices and now voicemails for different people are appearing on all 3 phones which is clearly very irritating, and a risk to confidentiality.

Any ideas how to get back to working properly? 

[MI5]

@etherp 

I'd start by signing out of your Apple ID's and logging back in again.

I'm also assuming each phone has it's own individual Apple ID?