In the telephone office
Every time you make a telephone call—either by dialing or by giving the operator the number—you first reach the telephone central office. This nerve center of your local telephone system contains equipment through which your telephone can be connected to any other telephone you wish to reach.
In a small community there may be only one central office. In large cities there are many of them, all joined by trunk lines. The term telephone exchange means the whole local area served by one or more central offices.
Over four-fifths of all Bell System telephones are dial-operated. Intricate machinery in the central office makes connections by obeying the electrical signals that you send over your line as you turn the dial on your telephone.
Before you dial, the equipment in the central office tells you it is ready to serve you by transmitting a “hum-m-m-m” over your line. You should hear this dial tone before you start to dial. The dial tone serves the same purpose as the operator’s “Number, please!”
Telephone company buildings are built to harmonize with surroundings in communities where they are located. A central office in California.
Another one in Connecticut.
Testing equipment in a dial central office in a large city.
Telephones that are not dial-operated are connected with manual central offices, where operators seated at switchboards make the connections by hand. Switchboards differ greatly in size. In small villages one or two operators handle all calls. In large cities the volume of calls requires hundreds of operators working at large multiple switchboards. The term multiple comes from the fact that the end of each subscriber’s telephone line is duplicated or multipled at intervals throughout the switchboard. For example, a switchboard serving 6,000 customers might have positions for 20 operators. The board would be multipled so that each operator answering a call from any of the group of customers assigned to her, could reach his line and connect it with any one of the 5,999 others.
Written as well as spoken messages are handled through switchboards. Teletypewriter Exchange Service (TWX) does for the written word what the telephone does for the spoken word. This service transmits typewritten messages over any distance through connections made by operators at switchboards. It is especially valuable for business firms; there are now some 37,000 listings in the TWX directory.
Typical traffic curve
City telephones are generally busiest between 9 and 11 A.M., when business is in full swing. There is another business peak between 4 and 5 P.M. Residence telephones are usually busiest about 7 P.M.
Operators, who answer when you dial “O” (operator), will lend a hand if you need help in calling from a dial telephone.
The courteous, helpful service rendered by telephone operators has become a traditional part of American life. Even in communities that have dial service, “the voice with a smile” is on the job to handle long distance calls, to provide telephone numbers not included in the directory, and to give any other help that customers may desire.
Ever since World War II, the Bell companies have kept on installing new equipment in great quantities to meet the largest demand ever experienced for new telephone service.