To provide context, I talked to *9* different Xfinity support personnel in the last week trying to get voicemail working. It had stopped at some point in the last few months. All were in extremely noisy call centers that, combined with their accents & my age made them difficult to understand. The last of the 9 said they couldn't fix the problem. I found solution on random webpage: call forwarding was enabled, unbeknownst to me. Turning it off solved the problem.
Stumbled on the solution on my own. Never did get that callback from xfinity. 🤷♂️