The usage guide says:
If you are having issues with Visual Voicemail, please be aware that AT&T USA users are unable to use this feature currently due to a lack of AOSP support. Other carriers are done on a best effort basis. We would suggest using Google Dialer with sandboxed Google Play if you are unable to get this feature working.
I have Consumer Cellular, with AT&T as the underlying carrier... VMM works fine there (recently added for CC - a few years ago they didn't). Is this a case of AOSP doesn't support it, but something in Google Play Services or similar does support it? (clearly something is)
If I don't give a fig about avoiding Play Services etc (which I don't) will I be able to use the VMM app that way?
VMM is a must have for me, when job hunting you need to use voice mail sometimes, and I am not about to deal with it via calling and the menu tree.