How many phone numbers were in the world’s first telephone book?
The Connecticut District Telephone Company issued its phone book just 11 months after its founding. Along with advertisements and business listings in the back of the book, the directory included the names and addresses of its 391 subscribers. There were no phone numbers. The service cost subscribers $22 per year and allowed calls up to three minutes. More than two calls per hour required specific permission from the central office. Source: HistoryofInformation.com