Stopped getting voicemails about a months ago

My iphone 12 just stopped getting voicemails about a month ago.  I'm not sure exactly when, because I don't typically get many.  People eventually just started asking.

My voicemail is set up.  It picks up the call and allows people to leave VMs.  They just never show up on my phone.  Even when I try to call my VM account, it seems to be set up fine. There are just never any VM messages there.

I've done everything that a google search recommends, including:

-make sure VM is set up

-changed outgoing message multiple times.  Sometimes, it just reverts back to the default message.

-restart

-reset network settings

- reset password

I even got a new phone, and it still doesn't work.  I'm out of ideas.  Any suggestions?