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

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

Paul Coxwell (
Sat, 01 Oct 2005 20:23:22 +0100

> 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.

Local numbering plans with 3, 4, 5 and 6-digits were all in widespread
use into the 1980s. All of these were straight numbers, with no
letters involved.

Up until at least the very early 1970s there were even some old UAX5
offices (Unit Automatic eXchange) in rural areas with 2-digit local
numbers. The UAX5 is quite a fascinating system in its own right, and
in fact I've just acquired a GPO manual for it dating from 1930, but
that's another story!

> 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.

> 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.

The changeover to all-figure numbers occurred during the 1966 to 1969
period. British dials of the time differed from American in having
the letter "O' on the digit zero. That resulted in the disadvantages
of not being able to use any office name beginning with "O" and that
it was impossible to come up with anything for the 66x prefixes (or
n66 for that matter). On the plus side, it meant that a zero could be
used as either the second or third digit of a prefix, and allowed
certain combinations of names which would not be possible under the
American system. For example, London had both MONarch (606) and
MOOrgate (600) exchanges.

In London, most of the older offices had names which related to some
geographical feature in the neighborhood, such as the name of a
suburb, a road, a park, a river, or other well-known building or
landmark. Toward the end though, exchange naming had to become more
creative, and names which were of no particular significance were
assigned. The poetical/literary series of office names is a good
example, such as BYRon (297), DICkens (342), and WORdsworth (907).

At the end of the 3L-4N era, there were approximately 250 prefixes
assigned to offices in the London director area. Another handful were
used as 3-digit service codes, e.g. DIRectory (347), TIMe (846), and
TELegrams (835). The GPO even used UMPire (867) for recorded cricket
scores at one point -- You'd KNOW you were in England then!

Of the 250-ish assigned C.O. prefixes, about 100 remained unchanged
during the conversion to all-figure numbering, including many (but by
no means all) of the offices serving the "City" and "West End" -- the
central financial and business districts of London. For example,
CHAncery, FLEet Street, GERard, and MAYfair all just went to their
numerical equivalents of 242, 353, 437, and 629 respectively.

The other 150-odd offices were assigned completely new prefixes with a
limited grouping of codes within a district. In the part of north
London where my family lived, there were offices named ENField (363),
ENTerprise (368), KEAts (532), and LABurnham (522). ENField and
ENTerprise kept their existing prefixes, while KEAts and LAburnham
became 366 and 360 respectively, putting all the 36x prefixes into the

Similarly, BARnet (227) and HADley Green (423) became 449 and 440,
putting them in the same 44x grouping as the nearby exchanges HIGhgate
Wood (444) and HILside (445), both of which kept their original

The new prefixes were assigned such that no new code conflicted with a
3L prefix which was being taken out of service, and in fact there was
a permissive dialing period. The hitherto unused prefix groups such
as 55x provided scope for changes where a whole bunch of offices was
to be renumbered. In fact under the 3L-4N system the following
"groups" were completely empty: 55x, 59x, 65x, 66x, 67x, 69x, 85x,
95x, 96x, 97x, 98x, and 99x (excluding the 999 emergency number). A
further eight such "groups" had only one prefix in use, e.g. 46x had
only IMPerial (467) and 56x had only KNIghtsbridge (564).

The 3L service codes migrated to the 1 level, e.g. 192 for directory
and 151 for fault reporting. (And in fact the former ENGineers
fault-reporting number was later used as the new 364 prefix serving
Winchmore Hill, a part of north London in the 36x grouping I mentioned

I'm not too familiar with the exchanges in the other director cities,
but I know they also changed some prefixes during the transition to
all-figure numbering. Birmingham, for example, renumbered some
offices so that north/south/east/west/central districts were
determined by the first digit of the prefix. They had an easier time
making new assignments outside of London though as fewer prefixes were
in use. Birmingham had, I believe, less than 50 central-offices at
the time of the changeover. I'm not sure of the figures of the
changeover arrangements for Edinburgh, Glasgow, Liverpool, or

> [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.

I don't recall ever seeing that number used in London, but it's
possible. Sometime after the change to straight 7D numbering, and
certainly by the early/mid 1970s the GPO was using the 246 exchange
for a range of recorded announcements in London (and some of the other
director cities). The most commonly used numbers were of the form
246-80x1, i.e. 246-8021, 246-8091, etc. I can't remember all the
assignments offhand, but they included local London weather, national
weather, theatre information, and various recorded information lines
for tourists.

In a lot of advertising in the 1970s, the GPO would use a 246 number
on the phone dial, in much the same way as the Bell ads used 555-2368.

I know that "WEather 6-1212" (936-1212) is still used in a few U.S.
cities, including Washington D.C. (202), Philadelphia (215), and
Milwaukee (414).

The days of the phone company providing recorded weather information
on a local number have gone over here. You can access it on an 09
premium-rate number from various private enterprises these days, but
given the easy access to weather information from various other
sources, you'd have to be pretty desparate to pay the equivalent of a
dollar per minute or more to do so.


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