"Martin Underwood" wrote in message
...
"Stephen Osborn" wrote in message
...
"Martin Underwood" wrote in message
...
"John Shelley" wrote in message
news Martin Underwood wrote:

The association of a single code with a geographic area disappeared
decades
ago. Harrow has the 8424, 8427, 8861 and 8863 codes. In the predigital
days I believe these were normally co-located in the same exchange
building.

Well it exists to the extent that there is one or more codes that relate
to
a specific geographical area (eg a town or a collection of neighbouring
towns/villages) but don't relate to anywhere else: given a phone code, you
can say which places use it[*]. Maybe the boundaries have become a bit
more
blurred and the regions have got larger (like a two-letter code in a car
registration number used to relate to a specific town, whereas now it
relates to a group of counties).


I said the association of a *single* code with a geographic area disappeared
decades ago.

In an earlier post there was a comment along the lines of
"my number was CHIselhurst xxxx, then 244 xxxx, then 01 244 xxxx ..."
and I was just saying that that simple linkage was long gone.

Two people move into adjacent houses (pre 2000) in, say, Harrow and one gets
a 424 xxxx and the other gets 863 xxxx. One thinks that the code for Harrow
is 424 and the other thinks it is 863 and *both* are wrong.

BTW, I do know that 244 is not used for Chislehust, I was just doing a
simple 2=A/B/C, 3=D/E/F ... substitution.


Nowadays the exchange equipment is orders of magnitudes smaller, so in
some
case your 'local' exchange is actually located in an exchange building
in
a
neighbouring area, along with half a dozen other 'local' exchanges.

Your 'phone line will physically be connected to a some sort of device
locally. However this could be a consolidation device that takes all of
those lines on to a neighbouring exchange building. Alternatively it
could
just take *some* of those lines to a neighbouring exchange building if
there
are logistcal reasons. For example the one room in the building still
being
used for exchanges only has room for three and a half sets of lines -
don't
forget that at some stage 9,999 lines have to be connected up to each
local
exchange.

To answer your specific question, I believe that anyone in Harrow will
get
one of the above codes *if one is available*. If not they will get one
form
one the exchange in the exchange building where their 'phone line ends
up.

What about the situation where the same code is used by several towns and
villages, each of which has a telephone exchange. My code is used by two
moderate-sized towns and many neighbouring villages. I know that my
village
has its own exchange (the building is about 100 yards from me right now!).

The building is still there but how much of it is still used for exchange
purposes?

Some have been sold off / leased out, with perhaps a new small brick 'shed'
holding the equipment that used to fill the building. Some, especially the
larger ones, have been converted into BT offices, with perhaps ... . Some
of the smaller ones have equipment in one room and the rest is used for
other purposes, storage, hot desks for non office based staff, etc.

Presumably some form of supernetting is used: the first one or two digits
of
the subscriber's number determine which exchange (consolidation device)
the
call is routed to.

I would make the same presumption but I don't actually know. My knowledge
is much more about numbering and about network infrastructure only as it
affects numbering.


regards

Stephen