Oh! I see what is going on. The article is a little unclear (Going to give the person who wrote it a-talking to and I'm 99% positive it was me). The part that is throwing you off, you have Sonic Fusion Fiber and the voicemail instructions you are reading and trying to follow along are for Sonic Fusion DSL.
While I fix that, for now.https://members.sonic.net/voice/Choose
your phone number
About mid screen you'll see a blue bar with Home Messages Contacts.
" and you can play the voicemails from there.