Patrick,
I'm not sure if you can help me but I've not been able to find information on when "unlisted" phone numbers first came to use.
I'm a novelist, working on my third book, and trying to find this info.
Can you help or point me in the right direction?
Many thanks,
Patricia
[TELECOM Digest Editor's Note: I do not know when they first got started, but I can tell you that in the 1922 Chicago Telephone Company alphabetical directory, on the page entitled "Services You Can Obtain From Our Business Office" non-published/unlisted phone numbers were available at the rate of an additional five cents per month. PAT]