Old London Telephone Exchange Names [telecom]

The only country where zero is one pulse is Sweden. New Zealand had the digits in the reverse order, but zero was ten clicks.

The reason that UK numbers generally start with 0 is the same reason that our numbers start with 1 -- it's the escape indicator that means it's not a local number and an area code (known in the UK as STD code) follows. They use codes starting with 1 for special services such as

112 which is similar to the North American 911.

R's, John

Reply to
John Levine
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I received an e-mail recently inquiring about the old

> exchange names in London, and thought a general posting > might be of interest.

[TELECOM Digest Editor's Note: My thanks to Paul for this

> special report which will be specifically filed in the > Archives history area. I should point out that Chicago, > Illinois also used the 3L-4D method of numbering until > about 1950 when it changed to 2L-5D for about ten years > before going entirely 7-D. Thanks again, Paul. PAT]

Back in the 60s I lived in Evanston and worked in Chicago. Even at that late date I occasionally noticed 3L+4D numbers on old signs or in publications.

- UNIversity, in Evanston, for Northwestern University.

- GREenleaf, in Evanston, for Greenleaf Street.

- BEVerly, in Chicago, for the local neighborhood.

- MIDway, in Chicago, for Midway Plaisance, a block-wide parkway running between Washington Park and Jackson Park. During the World's Columbian Exposition in 1893 it had been "the Midway". It splits the University of Chicago campus in half. The University's main number would have been MIDway 0800.

In most cases the 3L code matched the new 2L+1N code, but there were a few exceptions. In Evanston, what had been GREenleaf became GRreenleaf 5.

Neal McLain

Reply to
Neal McLain

New York City was originally 3L-4D, but had to switch to 2L-5D early on (around 1930) because growth was so rapid.

Philadelphia had 3L-4D but had to switch to 2L-5D right after WW II.

In the 1950s, many small towns could have any number of digits. With the coming of Direct Distance Dialing, every local phone number had to get expanded to seven unique digits, with a unique exchange code within the area code. Sometimes it just meant padding a two or three digit number with zeros, but other times it meant new numbers. Since all dial exchanges back then was electro-mechanical, it meant a great deal of new equipment and re-wiring. All of this was just to handle _incoming_ toll calls. Additional equipment was required to handle outgoing toll calls.

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My favorite example of leading zeroes would be Nelson, Nevada, an unincorporated community in Clark County south of Las Vegas. Google calls it "Nelson Ghost Town". According to Wikipedia the population is 37. The Census Bureau recognizes it as a "census-designated place" (presumably so they can count those 37 residents).

But Nelson has its own NPA-NXX thousand-number block: 702-291-0xxx. When I visited there back in the 90s, all Nelson phone numbers were in the range 702-291-00xx. A grand total of 100 possible numbers!

Most of the "electro-mechanical" equipment was some variation of Almon Brown Strowger's "up-and-around" switch, extensively utilized by GenTel and the Bell System during the 50s and 60s.

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With the introduction of nationwide toll dialing it was necessary for each exchange to utilize 7-digit directory numbers. An older

3-, 4-, 5-, or 6-digit Strowger exchange would be modified to accept inbound 7-digit numbers by adding "dummy" leading digits. For local calls the dummy digits were ignored ("absorbed") at the first selector by digit absorbers.

I have written about absorbers in previous T-D posts:

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Neal McLain

Reply to
Neal McLain

Le dimanche 21 août 2016 à 23:36:36 UTC+2, Neal McLain a écrit :

Hello Paul.

I do thank you for that useful post.

I added a link in the French Wiki devoted to the Parisian old exchanges :

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- see =C2=A7 6.2 and 11.3.

Kind regards.


Reply to
Poissons 1957

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