Post by Colum MylodIn fact it's a mix of 2 different policies[1]. Initial one was a copy
Thank you for an interesting reply. My interpretation of the situation
(without the benefit of the booklet you refer to) is slightly
different.
Post by Colum MylodInitial one was a copy of the British system: 1, 21, 41, 51, 61, 71, 91
I think this is more apparent than real. 021, 031, 041 etc bear no
relation to the location of the place concerned in the UK. The UK has a
large and complex network of routings and adopted a scheme using full
translation, therefore the code allocated (originally on an
alphanumeric basis similar to the then Director areas) was totally
divorced from the geographic location or routing of the call.
The Irish Republic who have a much simpler network adopted what is
known as the "Decade" numbering system. In this case the country is
divided up into up into areas (01, 02 - 09 etc) which are then further
subdivided (021, 022, etc). This works for a small country such as the
ROI with a small number of major trunk exchanges and routings between
them but was considered and rejected for Britain because it was
considered too inflexible for future network changes and the complexity
of equipment needed to work out direct or non-standard routings which
did not match the network hierarchy inherent in the numbering scheme
was such that it offered no advantage over a fully flexible scheme
using full translation.
On the other hand the Irish network is relatively simple with a
small number of trunk zone centres:
01 Dublin
02 Cork
03 reserved for direct dial calls to mainland GB
04 Drogheda
040 Arklow
050 Portlaiose
05 Waterford
06 Limerick
07 Sligo
08 reserved for direct dial calls to Northern Ireland
09 Galway
090 Athlone
these areas are then further subdivided, so giving rise to 0402, 0502,
0902 etc being the areas served by the switching centres at Arklow,
Portlaiose and Athlone. I assume this was attractive as the routing
table would have been relatively simple and may have been chosen to
minimise the use of expensive routing and translation equipment. In
theory, if a call is either routed direct of circulates via the zone
centres which are all interconnected, call routing is very simple
indeed (I suspect the practice was probably not quite as simple!).
Post by Colum Mylodand other original areas were very large; later ones followed the Dutch tiddly code sizes: Arklow, Wicklow, Gorey, Athlone etc are all later small areas The > inequality between Dublin's local call area and the sizes in the west was appalling.
I think this was more in the nature of population and telephone
distribution, the same is true of the large Director areas in this
country. 021, 041, 051 etc in Ireland are the areas served by the local
exchange and do not cover the whole 02, 04, 05 areas etc. I think the
Irish planned in the basis of an approx 12.5 mile circle from the main
exchange.
Post by Colum MylodComreg etc begun to equalise the areas, and now eliminate the 40x/50x anomalies.
Some years ago when the network was fully digital and local call
charging was introduced they changed from a local call being a call to
your code only to it being a call also to nearby exchanges in adjacent
STD areas (not necessarily the whole of the adjacent code area) so
local call charging is divorced from STD code area so equalisation of
areas for technical or growth reasons is not a factor.
Post by Colum MylodQuite why Athlone's total number length (3 + 5) exceeded Dublin's (1+6) for years is inexplicable.
Not so in the light of the above. It was often the case that the
capital city was allocated a short, memorable code (this also allowed
for expansion at a later date). Athlone was 0902 as it was a
subdivision of the 090 (Athlone trunk exchange area) and local numbers
contained 5 digits (it was 4 originally IIRC)
Post by Colum Mylod[1] An old on-line chum sent me a booklet explaining the design of the
Irish system. Indeed initial design was to copy the Post Office design
in Britain. A Dutch consultant invaded and contributed the later
longer codes/smaller areas. That lasted decades. Must dig up the
booklet.
I would be very interested to see a copy. Perhaps you could post the
salent points. I would also be happy to pay photocopy, P&P costs if
this were amenable to you (or indeed purchase the booklet).
Apologies for the long post. I hope it stimulates some discussion!
John