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.
Splicers “cutting in” wires in a new cable, below the street in manhole.
Bell telephone installer connects drop wire to new subscriber’s home.
Most wire in city telephone cables lies underground in tile conduits and comes into the telephone office through a cable vault in the basement. If the city has more than one central office, trunk cables interconnect the offices.
At each telephone office the cables run to the terminal room, where their hundreds or thousands of pairs of wires fan out to terminal blocks on one side of a large distributing frame. Other wires run from the opposite side of the distributing frame to the switchboard or dial equipment. Cross-connections on the distributing frame bring each telephone user’s line to its proper terminal in the switching equipment.
A telephone office is dependent on electric power, both direct and alternating. The direct current comes from storage batteries. These are kept charged by generators driven by the regular current supplied by the power company, which also provides the electricity needed for other purposes. Standby generators, usually driven by gasoline or diesel engines, are provided for emergencies in most large offices and in many smaller ones.
Ringing machines generate alternating current to operate your telephone bell and provide the various signals you hear in your telephone receiver. These machines are installed in pairs so that there will be no interruption of telephone service should one machine fail to operate properly.
Technicians check for trouble at a desk in a central office. Preventive maintenance, outside as well as inside telephone offices, helps provide good service.
Preventive maintenance, both inside and outside telephone offices, is vital in furnishing dependable, satisfactory telephone service. Telephone men periodically check the condition of telephone plant. Using steadily improving techniques, they often discover faults or weaknesses and have them corrected before the customer is aware of them.
Test desks, where testmen also track down troubles in the telephone plant, are essential to giving good service. These are special switchboards with equipment that enables the testman to diagnose the cause and location of trouble on a customer’s line.