Don't receive voicemail alerts when apple ID is on phone

Hello,

For a while I have not been receiving text notifications for left voice messages on my phone.

I did a factory reset and then set up the phone as a new phone, and I received text notifications. I then signed into my apple ID and the notifications stop - I have restored my phone to factory default and been through this process three times, and each time when not setting my phone up from a back-up or not signed into my apple ID I receive the notifications, when signed in or set up from a back-up I don't receive them.

All the correct notifications are enabled on my phone, I put my sim card in a friends phone and the same problem happens.

Any ideas?

Thanks