The first publication of telephone numbers – it was hardly a book, it only contained 50 names and was a single cardboard page – was printed on February 21, 1878 in New Haven, Connecticut by the New Haven District Telephone Company. The page did not include telephone numbers, it was really just a list of who could be contacted by phone. This was just two years after Alexander Graham Bell was granted a patent for the telephone

Here’s the list of early technology adopters.

Although there were earlier lists that showed phone companies’ business subscribers, this is considered the first phone book because it also lists individuals who had phone service.

Later that year, the New Haven Connecticut phone company published another phone book. This time it was 20 pages and listed 391 telephone subscribers. It also provided information about how to make and receive calls. All calls were limited to 3 minutes were not private. There were still no phone numbers listed, all calls had to be connected through the operator.
There is one known copy of this second phone book It was put up for  auction at Christie’s in 2008. They had anticipated a selling price of $30,000 to $40,000. It sold for $170,500.