3L-4N (was NYC History)

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On Fri 11 Aug 2006, Lisa Hancock asked:

Anyone familiar with this? > NYC got dial in 1922. It was set up as 3L-4N, that is, > PENnsylvania 1234. At some point it was switched to 2L-5N, that is, > PEnnsylvania 6-5000. Philadelphia switched in the mid 1940s. Would > anyone know when NYC switched? Did Chicago switch?


This has been asked and answered numerous times in the past in this forum. The most recent time seems to be last Fall, in September 2005, and I'll post exactly what I said back then to one of Lisa's posts:


From: Anthony Bellanga (email address suppressed) Date: 09/29/2005 07:42 PM Subject: 2L-4N, 3L-4N, 2L-5N Numbering

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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 mentioned.

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 digit.

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, 80s.

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.

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Anthony Bellanga
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