"Martin Underwood" wrote in message
...
"John Shelley" wrote in message
news
Martin Underwood wrote:
snip


Yeah, silly question, on reflection! I presume the equipment has to accept
a
fixed number of digits (previously seven, now eight) and identify the
first
four (previously three) as the district and the remaining four as the
subscriber number. If the stream of digits begins with a 0, an alternative
algorithm identifies from the digits that follow how many are the exchange
(eg "20" signifies London, "1344" signifies Bracknell). I can see that if
you only dial the final four digits, they could be confused with 0
signifying "what follows is an exchange" or 1 signifying special numbers
like emergency (112), directory enquiries (118xxx) etc.

Actually the local exchange simply routes all numbers that start with a 0 to
the associated trunk exchange (properly called a DMSU, for Digital Main
Switching Unit).

The DMSU does geographic mapping, routes the call to the relevant DMSU on
the other end which in turn routes it to the relevant local exchange.

If it is a non-geographic number (07*, 08*, 09*) the DMSU routes it to a
special platform that does really clever lookups. That is how a call to a
call centre number at 3am is answerd in India, at 3pm in, say, Sunderland
and at 11pm in the USA.

snip

digit exchange codes are actually located in the same building. Here in
Harrow the exchange building housed both the 8427 and 8863 exchanges and
probably others as well. With the arrival of electronic exchanges the
physical space needed for an exchange was vastly reduced so adding extra
switching capacity within a building that was built to house a
mechanical
exchange isn't a problem. The extra exchange numbers are also needed
for
the non BT operators.

Ah, so new suscribers in an area potentially get a brand new district
number
that's unrelated to that of all the other subscribers in that area? Yes, I
suppose that's one way of solving the problem. Do all subscribers in one
area get one new code and all those in another area get different code:
can
you still say "xxxx [a new code] is Harrow, alongside yyyy [the existing
code]" or is the code-to-location mapping lost?

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.

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.

regards

Stephen

"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).


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!).
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 used to work with a guys who was a walking look-up table. He had each
memorised the STD codes and could tell you the code for anywhere or which
places a code relates to (we tested him and he was spot-on every time!). As
if this isn't "sad" enough, he couldn't see that this skill was perceived as
"sad" rather than endearing him to people. He could also see a photo of a
car dashboard instrument (eg a speedometer) and tell you every make/model of
car that it had ever been fitted to.

"Martin Underwood" wrote in message
...

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).

Actually, to be pedantic, they still do (to a degree). The first character
is the registration district, the second is the registration office. So, for
example, in a registration such as AA54 ABC: AA indicates Anglia district,
Peterborough office (as would AB to AN). AO to AU are Anglia district,
Norwich office and AV to AY are Anglia district, Ipswich office.

"Jack Taylor" wrote in message
. ..

"Martin Underwood" wrote in message
...

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).

Actually, to be pedantic, they still do (to a degree). The first character
is the registration district, the second is the registration office. So,
for
example, in a registration such as AA54 ABC: AA indicates Anglia
district,
Peterborough office (as would AB to AN). AO to AU are Anglia district,
Norwich office and AV to AY are Anglia district, Ipswich office.

But once there would be far more offices, each with its own mark(s): now
they've merged the marks so you cannot tell so accurately where a car was
registered.

I know the situation in Yorkshire better than Anglia: at one time UA, UB, UM
were Leeds, YG was Bradford, CX was Huddersfield and HL was Wakefield. These
were merged so that all these letters signified "somewhere in West
Yorkshire". I think the size of the region covered was further increased
with the new-style AA05 BBB numberplates. I'm not sure why they even
bothered to use new letters: the A123 BCD format had a two-letter location
code (CD) so why not continue to use the same code in the new-style
numberplates? Methinks that they took the opportunity to rationalise (merge)
some of the issuing offices at the same time.

And of course so many cars have personalised numberplates these days that
you often cannot tell anything about a car's age or place of "birth".

I'd better shut up or you'll be thinking that I'm as obsessive as my mate
the walking look-up table ;-) Oh, too late...

"Martin Underwood" wrote in message
...

But once there would be far more offices, each with its own mark(s): now
they've merged the marks so you cannot tell so accurately where a car was
registered.

True. Then again, it had become quite meaningless anyway with large-scale
commercial registrations or with garage chains registering vehicles in their
head office area before shipping them to their salesrooms.

I know the situation in Yorkshire better than Anglia: at one time UA, UB,
UM
were Leeds, YG was Bradford, CX was Huddersfield and HL was Wakefield.
These
were merged so that all these letters signified "somewhere in West
Yorkshire". I think the size of the region covered was further increased
with the new-style AA05 BBB numberplates. I'm not sure why they even
bothered to use new letters: the A123 BCD format had a two-letter location
code (CD) so why not continue to use the same code in the new-style
numberplates? Methinks that they took the opportunity to rationalise
(merge)
some of the issuing offices at the same time.

Yes, Yorkshire is an oddity in the new system, in that the Yorkshire
registration district only covers South and West Yorkshire (YA to YO being
Leeds office and YP to YY being Sheffield office). For some reason East and
North Yorkshire are lumped in with Teesside and Tyneside as the North
registration district, split into three offices (NA to NM at Newcastle, NN
to NT at Stockton and NU to NY at Beverley).

And of course so many cars have personalised numberplates these days that
you often cannot tell anything about a car's age or place of "birth".

Whoever decided that '0' should represent March registrations and '5'
October? What happens if, at some time in the future, they decide to use
every month as a registration month?

I'd better shut up or you'll be thinking that I'm as obsessive as my mate
the walking look-up table ;-) Oh, too late...

I wouldn't dare suggest such a thing! Especially from someone who has the
registrations table saved in a Word document!! ;-))

Have a Happy New Year, Martin.

"Jack Taylor" wrote in message
. ..

"Martin Underwood" wrote in message
...

True. Then again, it had become quite meaningless anyway with large-scale
commercial registrations or with garage chains registering vehicles in
their
head office area before shipping them to their salesrooms.

And of course there's the notorious dodge used by most coach companies: they
register their coaches in Northern Ireland which for some strange reason has
never adopted any of the ABC 123A, A123 ABC or AB05 ABC formats used by the
rest of the UK - hence their coaches don't bear any recognisable clue about
their age, to prevent the punters worrying about travelling on 10-year-old
(but imacculate) coaches. Take a look at the next few coaches you see, and
you'll see that I'm right!

I know the situation in Yorkshire better than Anglia: at one time UA, UB,
UM
were Leeds, YG was Bradford, CX was Huddersfield and HL was Wakefield.
These
were merged so that all these letters signified "somewhere in West
Yorkshire". I think the size of the region covered was further increased
with the new-style AA05 BBB numberplates. I'm not sure why they even
bothered to use new letters: the A123 BCD format had a two-letter
location
code (CD) so why not continue to use the same code in the new-style
numberplates? Methinks that they took the opportunity to rationalise
(merge)
some of the issuing offices at the same time.

Yes, Yorkshire is an oddity in the new system, in that the Yorkshire
registration district only covers South and West Yorkshire (YA to YO being
Leeds office and YP to YY being Sheffield office). For some reason East
and
North Yorkshire are lumped in with Teesside and Tyneside as the North
registration district, split into three offices (NA to NM at Newcastle, NN
to NT at Stockton and NU to NY at Beverley).

And of course so many cars have personalised numberplates these days that
you often cannot tell anything about a car's age or place of "birth".

It probably says something about my personality, but if someone offered me a
personalised numberplate I'd say no thanks: if a code exists, it seems only
right to use it and not to buck the system. Plus I don't want my car to
stand out from all the rest.

Whoever decided that '0' should represent March registrations and '5'
October? What happens if, at some time in the future, they decide to use
every month as a registration month?

I presume that this possibility was considered and rejected when the
numbering scheme was planned. The code that they've used is quite cunning:
for vehicles registered between March and September, the two digits are
always the last two digits of the year; for vehicles registered between
September and March, the two digits are always (year of the September) + 50.

I'd better shut up or you'll be thinking that I'm as obsessive as my mate
the walking look-up table ;-) Oh, too late...

I wouldn't dare suggest such a thing! Especially from someone who has the
registrations table saved in a Word document!! ;-))

Have a Happy New Year, Martin.

And you!

PS: I have to confess that I have all the STD codes saved as a Word
document, mainly so that if someone gives me a phone number I can tell
roughly where it relates to...

"Martin Underwood" wrote in message
...

The code that they've used is quite cunning:
for vehicles registered between March and September, the two digits are
always the last two digits of the year; for vehicles registered between
September and March, the two digits are always (year of the September) +
50.

What I still don't understand is what is going to happen in March 2011, if
they continue with the present logic, which is to use '0' to indicate March
registrations and '5' to indicate September and the other digit to represent
the last digit of the year! There will still be plenty of vehicles on the
road registered in March 2001 as aa01 abc. Should be interesting!

On Fri, 31 Dec 2004 20:35:21 -0000, "Jack Taylor"
wrote:

Whoever decided that '0' should represent March registrations and '5'
October? What happens if, at some time in the future, they decide to use
every month as a registration month?

Because the system will last 49 years (or thereabouts) as it is
without a change being required (though one may well be introduced
anyway, knowing the Government!).

Neil

--
Neil Williams in Milton Keynes, UK
When replying please use neil at the above domain
'wensleydale' is a spam trap and is not read.

"Martin Underwood" wrote in message
...

I know the situation in Yorkshire better than Anglia: at one time UA, UB,
UM
were Leeds, YG was Bradford, CX was Huddersfield and HL was Wakefield.
These
were merged so that all these letters signified "somewhere in West
Yorkshire". I think the size of the region covered was further increased
with the new-style AA05 BBB numberplates. I'm not sure why they even
bothered to use new letters: the A123 BCD format had a two-letter location
code (CD) so why not continue to use the same code in the new-style
numberplates? Methinks that they took the opportunity to rationalise
(merge)
some of the issuing offices at the same time.

The 1966 vehicle registrations letters can be found on my web site, in a
link from http://www.btinternet.com/~terry.harper/gallery.htm at the bottom
of the page. There were earlier lists which used to appear in each year's AA
handbook. Back when H and HX and lots of Mx combinations were Middlesex, for
example.
--
Terry Harper, Web Co-ordinator, The Omnibus Society
75th Anniversary 2004, see http://www.omnibussoc.org/75th.htm
E-mail:
URL: http://www.terry.harper.btinternet.co.uk/

"Terry Harper" wrote in message
...
"Martin Underwood" wrote in message
...

I know the situation in Yorkshire better than Anglia: at one time UA, UB,
UM
were Leeds, YG was Bradford, CX was Huddersfield and HL was Wakefield.
These
were merged so that all these letters signified "somewhere in West
Yorkshire". I think the size of the region covered was further increased
with the new-style AA05 BBB numberplates. I'm not sure why they even
bothered to use new letters: the A123 BCD format had a two-letter
location
code (CD) so why not continue to use the same code in the new-style
numberplates? Methinks that they took the opportunity to rationalise
(merge)
some of the issuing offices at the same time.

The 1966 vehicle registrations letters can be found on my web site, in a
link from http://www.btinternet.com/~terry.harper/gallery.htm at the
bottom
of the page. There were earlier lists which used to appear in each year's
AA
handbook. Back when H and HX and lots of Mx combinations were Middlesex,
for
example.

Gosh, I'd forgotten that single letters could also be used to denote the
place. Mind you, the whole subject of pre-1963 number plates and the variety
of forms that were used over the years has got me baffled. Interesting to
see that the code included the Republic of Ireland at that time, before the
modern 05-D-12345 or 03-WX-12345 format came into being, the letter/letters
denoting the county - Dublin and Wexford in my example.

Why do modern diaries not carry this list: it used to be in the front of
every pocket diary at one time.