Eleven months after its foundation, in November 1878 The Connecticut District Telephone Company of New Haven, Connecticut issued the world's first telephone book. The telephone directory contained the names and addresses of 391 subscribers who paid $22 per year for service. There were no phone numbers, but there were advertisements and listings of businesses in the back of the book—the first, embryonic "yellow pages." The advertisers included physicians and carriage companies. Customers were limited to three minutes per call, and no more than two calls an hour without permission from the central office.
"Besides rules, the embryonic phone book also featured pages of tips on placing calls — pick up the receiver and tell the operator whom you want — and how to talk on this gadget. Having a real conversation, for example, required rapidly transferring the telephone between mouth and ear.“When you are not speaking, you should be listening,” it says at one point. You should begin by saying, “Hulloa,” and when done talking, the book says, you should say, “That is all.” The other person should respond, “O.K.” Because anybody could be on the line at any time, customers should not pick up the telephone unless they want to make a call, and they should be careful about what others might hear. “Any person using profane or otherwise improper language should be reported at this office immediately.”