Another mystified customer in Vermont... I don't need roaming because the phone I have on this Verizon account is a Verizon Home Phone that operates off a small wifi modem that sits on the table next to the telephone unit. I keep getting this message which appears to be some kind of block. But when I call again sometime later, I can get through. I have not had any luck with tech support, they seem to know nothing about it. The service is cheap for the Home Phone but I guess you get what you pay for, right? And sometimes you DON'T get what you are paying for!
I also notice that if I dial an in-state number it can make a difference whether I add the area code or not. There are several small local telecom companies operating and they all seem to have their own rules, canned messages, etc.
Just another quirky thing about Vermont (we're full of quirks).