TELECOM Digest OnLine - Sorted: Re: Telephone Area Codes and Prefixes

Re: Telephone Area Codes and Prefixes
16 Feb 2007 07:29:28 -0800

TELECOM Digest Editor noted in response to Neal McLain

> When automation finally started, in 1938, Illinois Bell started
> printing all numbers (dialable or still manual) in the telephone
> directory as names plus FOUR digits, using leading zeros as required
> to complete the string. ... from 1938 until 1946 Chicago was about
> 20-50 percent dial and the same amount manual. PAT]

Just wanted to a note another reason why they did this: The Bell
System plan for large cities was the "panel system". They knew it
would not be converted to dial overnight. Also, cities and suburbs
were growing and modest manual exchanges could soon grow into big
exchanges. (In the 1920s the cities were developing new dense
neighborhoods rapidly). The panel system was designed to provide for
all of this.

The panel system was 'common control' in that it had some intelligence
designed into it. Unlike step-by-step where each dial pull controlled
the direct switch, panel stored the number in a register, translated
it to proper routing, and made a connection from the translation.
This gave the necessary flexibility for city networks.

Panel also provided automatic assist for dial-manual interconnections.
The idea was that dial customers would not need to know the type of
exchange they were calling, they would dial the 7 digit number in all
cases. If they were calling a manual office, the system would route
the call to the exchange, and convert the last 4 digits to a readout
on the operator's switchboard. The manual operator would make the
connection based on the readout. For calls from a manual exchange,
the operator would merely dial the desired number. (I'm simplifying
this quite a bit).

As an aside, for some reason I don't understand, panel could NOT be
used for Centrex service, though the older step-by-step could (along
with crossbar and ESS). In SxS, they merely wired the terminating
selectors to serve as the Centrex switch, very simple. I don't know
why panel's logic circuits couldn't handle it.

In the literature, it says a manual exchange could have 10,500 numbers
and an extra digit was provided for that. How often that was used in
reality I don't know; perhaps just in NYC with its very high density

Panel also provided meters to count up local calls to charge message-
rate service.

I believe (need to confirm) the meters were also used to time calls in
NYC, that is, after say five minutes, the meter incremented again. As
to suburban calls, the meters would work out fine for message units,
but calls still may have been internally processed with full AMA
details even if the customer only saw a meter count, not itemization.

(To this day, city suburban calls are charged by message units or
"measured service", in which units are changed based on distance and
time. The customer doesn't see itemization of a bunch of 15c and 25c
calls, rather just an accumulation. In Phila, the Verizon reduced the
charges, widened the free area, and gives off peak discounts.
However, the basic system remains in place to this day unless you buy
a wide area calling package. Consult the front of the Verizon
Philadelphia phone directory for details.)

(For myself, national unlimited was only a few dollars more than local
wide area, so I now have national unlimited. For someone who
remembers when making a long distance call was serious business, free
calling is a bit strange and takes some getting used to.)

[TELECOM Digest Editor's Note: The single, isolated example I ever saw
of a manual phone with FIVE digits after the exchange name was in
Hammond, Indiana when I was about 11-12 years old. A payphone in the
parking lot of a grocery store carried the number 'Sheffield 10523'.
Note that was NOT 'Sheffield-1' but rather, a manual exchange
'Sheffield' followed by '10523' as the number within the exchange.
Hammond, the first of the Indiana cluster of Chicago southeast
suburban suburbs to 'go dial' about 1953-54 converted their Sheffield
exchange to WEstmore 1 and WEstmore 2; and their Russell exchange to
WEstmore 3 and TIlden 4. And in those days, WEstmore and TIlden
anything could seven digit dial Illinois-side south suburbs, and vice-
versa, but Chicago itself required the leading 219 to call Indiana.
For many years, there was no 312-931, 312-932, or 312-933 since those
would have conflicted with Hammond's exchanges. Bell finally cut in
312-659 (Whiting, IN has 219-659) in 1982 and gave it to Cellular One for
cell phones. Now it is no longer '312'; I suppose now it is 773 or
maybe 630. PAT]

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