TELECOM Digest OnLine - Sorted: San Francisco and Oakland Exchange Numbering

San Francisco and Oakland Exchange Numbering

Anthony Bellanga (
Thu, 29 Sep 2005 19:07:55 -0600

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please REMOVE my email address from display in the "from" line, AS
WELL AS in the "reply to" line.

Regarding Lisa Hancock's post on Oakland and San Francisco and
2L-4N numbering ...

Los Angeles had mixed 2L-4N and 2L-5N from the 1920s thru the
mid/late 1950s.

Toronto ON was 2L-4N and began phasing to 2L-5N in the early 1950s
thru mid-1950s.

and so forth ...

Wes Leatherock posted about all kinds of mixed numbering/dialing plans
in various cities. There was no real consistancy to numbering plans
until the later 1950s when the Bell System began plans to introduce
customer originated Direct Distance Dialing.

San Francisco and Oakland were 2L-4N thru at least the end of WW-II
(i.e., mid-1940s). I don't know if the entire area was flash-cut to
2L-5N or if it were phased, and if it were phased over, how long it
would have taken.

BTW, when I say "phased", I am *NOT*, repeat *NOT* referring to a
permissive dial period. NO, "phased" means that each individual
c.o.building would covert all of its own c.o.names into a "common
name", or add a new "third digit" to existing names in the same
building, on a FLASH-cut basis.

Maybe two or three exchange buildings would "flash cut" to 2L-5N
on the same Saturday night / Sunday morning....

But it could take a year or several years (five years in the case of
the some metro areas, 1955-60) for ALL exchange buildings to each
individually FLASH cut their 2L-4N numbering over to 2L-5N.

San Francisco / Oakland would have fully cutover to 2L-5N by 1950 (if
not 1949 or 1948 or so).

Remember that SF/Oakland was one of the 15 or so metro areas that were
customer-dialable from Englewood NJ starting in November 1951. ALL of
those areas that were customer-dialable from Englewood NJ were on a
full 2L-5N basis, just look for the booklet instructions that was
posted to the Telecom Digest Archives some years ago.

All of the SF/Oakland Bay area (except for some of the more outlying
communities which were also part of the customer dial plan) dialed
each other on a 2L-4N basis prior to the "cut" in the later 1940s, and
then on a "standard" 2L-5N basis afterwards. There were *NO*
code/name/letter conflicts! (The more outlying areas that were
customer dialable with SF/Oakland had special one/two/three-digit
"access codes" or prefix codes that needed to be dialed before the
2L-5N number).

I don't have any documentation for the "exact" reason, but for the
Englewood NJ customer dialing program staring in Nov.1951, San
Francisco and west bay communities (including those north of the
Golden Gate) were dialed from Englewood NJ by customers as 318+2L-5N.
Oakland/East Bay customers were dialed from Englewood NJ by customers
as 415+2L-5N.

I don't know if this difference in NPA codes was for routing purposes,
or for discrete ratings purposes, or a combination of both. HOWEVER,
OPERATORS who called the Bay Area, regardless of which side of the Bay
the desired called customer was located in, was reached as 415+2L-5N.

I don't know exactly "when" Bell reclaimed 318 from use by Englewood
NJ customers though ... I guess by the mid-1950s (maybe as early as
1953?) they started dialing 415+2L5N for ALL Bay Area numbers that
could be reached by CUSTOMER dialing.

Bell System journals of the early 1950s which dealt with Area Codes,
DDD, etc. always referred to JUST 415 if there was a map included in
the article. The use of 318 was only for instructions for Englewood NJ
customers. But again, the use of 318 *AND* 415 for this situation was
*NOT* because of any potential duplication of
... since both sides of the Bay could already "locally" dial each
other on a "pure" 2L-5N basis (and quite possibly a "pure" 2L-4N basis
prior to the mid/late 1940s).

By 1957, 318 was officially assigned to the (first) split of 504 in
Louisiana. 318 covered all of northern and southwestern Louisiana,
until 337 split off from 318 in 1999. 318 now covers only northern and
central Louisiana (Shreveport/Alexandria/Monroe), while 337 covers
south-central (Lafayette) and southwestern (Lake Charles) Louisiana.

- Anthony

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