TELECOM Digest OnLine - Sorted: Re: Early Los Angeles Dialing and Network Management

Re: Early Los Angeles Dialing and Network Management

Steven Lichter (
Wed, 17 Aug 2005 23:57:12 GMT wrote:

> The Bell System history tells that they recognized the traffic of big
> cities would not fit on Step-by-Step switching because of the switch's
> limited decimal choices. Panel switching was developed to give more
> flexibility and choices in city service.

> However, Los Angeles remained Step by step because the Bell System
> inherited existing exchanges. The history says despite things like
> graded multiples network mgmt in LA proved difficult, but they did not
> elaborate.

> I know Bell Labs developed SxS add-ons in the 1960s and 1970s to
> improve SxS functionality, but that was much later. An early short
> haul toll itemized message accounting system was developed for LA.

> As Los Angeles turned into a big city (1950s?), how did the Bell
> System handle inter-exchange traffic within the limits of an SxS
> switch? Did they rely on tandems? Did they have to overtrunk at high
> expense? Did they put in No 5 Crossbar when it came out?

> Thanks.

> [public replies, please]

I believe they started using digit absorbing switches and directors
which did translations, so say you dialed a short hall number it would
drop back into the local switch, or to a trunk for another office, if
it were long distance it might go to a tandem. They as GTE did would
rearrange trunking for what was called the busy season.

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