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.