TELECOM Digest OnLine - Sorted: 2L-4N, 3L-4N, 2L-5N Numbering

2L-4N, 3L-4N, 2L-5N Numbering

Anthony Bellanga (
Thu, 29 Sep 2005 19:42:33 -0600

In an ongoing effort to TRY to eliminate or at least reduce $pam,
please REMOVE my email address from display in the "from" line, AS
WELL AS in the "reply to" line.

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

Numerous cities and large towns throughout the US and Canada developed
with 2L-4N numbering, sometimes mixed with 2L-5N as previously

Only the largest of cities actually had 2L-5N numbering from the
earliest days of local dialing within those cities or metro areas.

As for 3L-4N, only four cities in the US (none in Canada) ever used

New York City during the 1920s had 3L-4N, but changed to 2L-5N around
1930 or 1931. I don't know how consistant New York Telephone was
regarding the third dial pull letter being converted to a digit, i.e.,
was it the actual digit that the original letter corresponed to, or
was it something different, and if the latter, were there some few
cases where the third letter actually did convert to the corresponding

Philadelphia changed from 3L-4N to 2L-5N shortly after WW-II, either
1945 or 1946. In MOST cases, the third letter changed to a numerical
digit that did NOT correspond to the original letter. But there were
a few cases where the conversion to a digit did correspond to the
original third letter.

Chicago changed from 3L-4N to 2L-5N around 1948; Boston changed from
3L-4N to 2L-5N around 1949. My understanding for both Chicago and
Boston, is that in most cases, the third dial-pull letter did
changeover to the corresponding digit, but there were some exceptions.

There were a handful of cities in the United Kingdom which had 3L-4N
numbering. Every other place in the UK had less-than-seven digits
(or dial pull) local numbering throughout the 1940s, 50s, 60s, 70s,

These UK locations that did have 3L-4N were the "director" cities,
the largest of all metro areas, and also had the shortest STD codes
ending in a '1' (or having the only digit of '1').

(0)1 London
(0)21 Birmingham
(0)31 Edinborough (SCOTLAND)
(0)41 Glasgow
(0)51 Liverpool
(0)61 Manchester.

Note that (except for London with just the digit '1' as its
significant STD code digit), that the first digit of the STD code also
corresponded to the first letter of the town:

(0)B-1 Birmingham
(0)E-1 Edinborough
(0)G-1 Glasgow
(0)L-1 Liverpool
(0)M-1 Manchester

Circa 1990, London split into "inner London" (0)71, and "outer London"
(0)81. Circa 1994/95, most STD codes in the UK had an extra digit '1'
tacked onto the front (following the leading '0' indication digit),
although some completely changed to new STD codes with a '1'.

Starting circa 2000, the largest cities in the UK changed their local
numbering plans (and dialing plans in some cases) as well as their STD
Code -- particularly London:

(0)171 + NXX-xxxx (inner London, seven-digits) changed to
(0)20 + 7NXX-xxxx (note the first new digit of the eight-digit number
begins with '7', that '7' signifying the old 1990s era STD code)

(0)181 + NXX-xxxx (outer London, seven-digits) changed to
(0)20 + 8NXX-xxxx (note the '8' in the old STD code and the '8' as the
first digit of the new eight digit local number)

Paris FRANCE also had 3L-4N (later seven-digits) at one time, the
change to 7-digit ANC (All Number/figure calling/dialing) took place
in the early to mid-50s. I think that ANC format numbers corresonded
exactly to the previous letters of the exchange names.

In the UK (at least London), they actually numbered previously named
EXChanges with totally different numerics, possibly to "force" people
to think of telephone numbers now as numericals, not with letters.

I can't think of any other places in the world ever having had 3L-4N.

- Anthony

[TELECOM Digest Editor's Note: Didn't London, England also use
WEATHER (seven letters, seven digits) for the recorded weather
forecast at one time? I know that Chicago used WEAther-1212 for
the recorded forecast at one time. Chicago began their conversion
to dial from manual in 1939, doing one or two exchanges at a time.
Then in 1942, with the advent of the war, when the United States
government nationalized Bell System for the duration of the war,
conversion was halted to be resumed again in 1946. However, in
1939 when conversion first began, some changes in the numbering
was done to have 'consistency' for everyone in the 3L-4D scheme of

Throughout the war, Chicago was partially dial and partially
manual. Manual customers could reach dial customers by just asking the
operator for the number; for dial customers to reach manual customers,
there were three digit codes which connected them 'as though they were
manual customers' to the desired central office, ie, '311', '511' 711'
etc. After dialing the desired three digit access code, they then
spoke to the operator and gave their request. During the war, in
addition to '211' being used for 'long distance', '811' was used
for 'priority long distance', that is, for government employees,
usually military personnel who were allowed to take over needed
circuits for calls when circuits were otherwise all busy. When the
war ended and things got back to normal, '811' was kept as an
alternate way of reaching '211' when 'time and charges' were needed
by the customer. PAT]

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