Martin Underwood wrote:
snip
By the way, how much of a London number can you omit? You can omit
the 020 if you're calling from a London number but can you also omit
the district code (the next four digits) if you're calling another
number in the same district?

You have to dial the 8 digits. Think for a moment, how does the equipment
know that the 4 digits entered is a local number and not somebody having a
pause between "dialling" the exchange and the subs number.

By the way, how did changing from 0171 xxx yyyy or 0181 xxx yyyy to
020 7xxx yyyy or 020 8xxx yyyy help alleviate the shortage of
available numbers in London? It didn't increase the number of
available phone numbers - all it did was to change the mapping
slightly. OK, so there's scope for additional district codes
beginning with digits other than 7 or 8, but it's not districts that
are in short supply, it's subscriber numbers (the xxxx in the above
example).

In precisely the way you say. Instead of 2 x 10,000,000 numbers there are
now100,000,000. As to the point that it's not exchange codes that are in
short supply. but subscriber numers, all you do is add another exchange
number to an area, creates another 10,000 subscriber numbers. Many of the 4
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.


--
Cheers for now,

John from Harrow, Middx

remove spamnocars to reply