File:Bell telephone magazine (1922) (14752929231).jpg

Identifier: belltelephonemag4344amerrich (find matches)
Title: Bell telephone magazine
Year: 1922 (1920s)
Authors: American Telephone and Telegraph Company American Telephone and Telegraph Company. Information Dept
Subjects: Telephone
Publisher: (New York, American Telephone and Telegraph Co., etc.)
Contributing Library: Prelinger Library
Digitizing Sponsor: Internet Archive

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solid-state science; the ferreedswitch, which came from the inventionand continued development of relays andswitches and basic investigation of the nature of magnetic materials. Pioneeringdevelopment of computer programingtechniques, quality control methods andtheory, mathematical simulation methodqto prove design ideas, and even errorcorrecting codes developed for digitaltransmission were necessary contribu-tions. It took a lot of different scientificdisciplines, many inventions and inno-vations, and close cooperation betweenthe various units of the Bell System todevelop and perfect ESS. ^ The telephone switching network is.after all, the worlds largest ma-chine and the worlds most complex oneto boot. One of its characteristics is therequirement that it must grow and changewhile it is operating—it cant be shutdown. Consider, for a moment, how thetelephone system grew. The first switching systems were man-ual switchboards. Operators used plugsand jacks to interconnect lines. As the
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Four men who have led in thidevelopment and perfection ofESS. Left to rii;ht are: WilliamK e i s t e r , director. ElectronicSwitching Systems EngineeringCenter: Raymond W. Ketch-ledge, director. ElectronicSwitching Laboratory: H. EarleVaitghan. director. ElectronicSwitching System Center; Wil-liam H. C. Higgins, executivedirector of Bell LaboratoriesElectronic Switching Division. number of customers grew, the job gottoo complex for such manual operation,and the first automatic switching centerswere developed. Early dial offices usedpulses from the telephone dial to acti-ivato a series of stepping switches in thecentral offices. Such systems, which aretstill in wide use, are called step-by-step.! While step-by-step switching is rela-;tively inexpensive and reasonably reli-able, it is also relatively slow andinflexible, and it does not use the switch-ing network at top efficiency. Because ofits inflexibility, it cannot convenientlyhandle some of the newer services whichcustomer may wan

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