How to top Voicemails from appearing on both iPhones.

I have an iPhone 12 (personal phone) and an iPhone 7 (phone from work). The phones have different numbers and SIM cards. They are both linked to my iTunes accounts. However the settings on my work iPhone 7 only allows my calendar to be shared. Before I updated to iOS 17, voicemails on the two iPhones were completely separate. Each iPhone would only show voicemails that were left on that iPhone . After I updated both iPhones to iOS 17, all voicemails from each iPhone show up on both iPhones. If I delete a voicemail on one iPhone , it is deleted on the other iPhone.

How can I correct this so that voicemails only appear on the iPhone that was received the call? I want to keep the voicemails separate on each phone.