I think we actually had that, bought on a whim by my Dad at a computer show in the 90's. We had some fun looking up how many people with certain first/last names were in the US, but didn't have much other use for it.
And funnily enough, family members of mine have started multiple businesses named A-1 something. :)
I don't know, but I'm also not entirely sure how phone books sorted back in the day (they predate ASCII by quite a bit), or if it was even consistent across locales (probably, at least before the baby bells), so for all I know A- sorted before A+, and nobody wants to be just A-.
And funnily enough, family members of mine have started multiple businesses named A-1 something. :)