On Friday, August 19, 2016 at 9:11:51 AM UTC-5, HAncock4 wrote:
[snip]
In the 1950s, many small towns could have any number ofMy favorite example of leading zeroes would be Nelson, Nevada, an unincorporated community in Clark County south of Las Vegas. Google
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.
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!
Since all dial exchanges back then was electro-mechanical, it meantMost of the "electro-mechanical" equipment was some variation of Almon
a great deal of new equipment and re-wiring. All of this was just
to handle _incoming_ toll calls.
Brown Strowger's "up-and-around" switch, extensively utilized by
GenTel and the Bell System during the 50s and 60s.
https://en.wikipedia.org/wiki/Strowger_switch
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: https://groups.google.com/d/msg/comp.dcom.telecom/hUBAP8WzrNc/QYbcLVxHavMJ https://groups.google.com/d/msg/comp.dcom.telecom/eRvBdpAU62w/oNhgyqO1EXEJ
Neal McLain
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