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. [Illustration: 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._] [Illustration: _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. Where the wires go The arrangement of wires that connects your telephone with the central office and with the telephones of other subscribers is something like a tree. Just as twigs lead to branches, branches to limbs, and limbs to the trunk, so individual telephone wires come together in small _distribution cables_. In turn, these cables come together in _feeder cables_ that increase in size as they approach the central office. Often as many as 2,121 pairs of fine copper wires enter the telephone office in main feeder cables about as big around as a baseball bat. [Illustration: _Splicers “cutting in” wires in a new cable, below the street in manhole._] [Illustration: _Bell telephone installer connects drop wire to new subscriber’s home._]