File:Bell telephone magazine (1922) (14754448394).jpg

Identifier: belltelephonemag26amerrich (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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ssifi-cations. Those designated as ClassOne are strategically located on maincircuit routes. There are about 350of these. The rest are groupedaround these Class One offices, andare called Class Two. In every Class One office, there is a simple route sheet which shows theroute to every other Class One office,and many of these are direct routesbetween Class One toll centers. Ifyou wanted to know the route to amost remote locality, all youd haveto know is the toll center and theClass One office through which it isreached. Both of these you couldfind in the Rate and Route Guide forevery point. Actually, in the day-to-day job youwould need to refer to the Guideonly rarely—on generally less thanfive percent of the calls. Routingbulletins, provided at each position,show all direct circuit points and asmany of the others as can be use-fully included. In addition there isa quick reference file at the RouteDesk which lists additional places. Percentage-wise, here is the wayit breaks down :—
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Erecting a crossbar Jrame in the Long Lines building in New York 184 Bell Telephone Magazine WINTER The routing of 82 percent of long Nation-wide Numbering Plan distance calls is direct. Frequently analternative route is provided throughan intermediate office. Calls zvhich go through one inter-mediate office are about 16 percent ofthe total, and there is often an al-ternative route through a different in-termediate office. The rest of the calls, less than twopercent, require tzvo or more switches.These usually involve far distant orvery small places between which thereis infrequent calling. Circuit engineers and control bu-reaus constantly study the flow oftraffic, and in order to maintain abalanced load on available circuitgroups, routing arrangements un-dergo frequent change. Circuits areshifted from group to group. Newdirect circuit groups are created.And traffic is routed to other groups.To meet changes in traffic distribu-tion between day and evening pe- Under operator toll diali

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