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.” —NYT