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## Re: New module Algorithm::Interval2Prefix

From:
Phil.Moore
Date:
December 4, 2003 10:50
Subject:
Re: New module Algorithm::Interval2Prefix
Message ID:
16335.33221.288720.817331@zappa.ms.com
```>>>>> "Lars" == Lars Thegler <lars@thegler.dk> writes:

Lars> I totally agree that when generating prefixes from number
Lars> intervals, this depends squarely on the involved numbers being
Lars> the same number of digits.  But telephone numbers *will* be the
Lars> same length in the same prefix-area[2].

Lars> [2] Since this is the only way the telephony switch can know
Lars> when the number you are dialling is 'complete'.

That's not true in Japan, where the area codes are variable length.
The local numbers are fixed, so they can make that decision (when the
complete number is dialed) after they have parsed the area code.

The way I beleive it works (I lived in Japan from 1988 to 1994, but I
beleive this is still true today), is that the length of the area code
depends on the 2nd digit.

All area codes start with 0, so if you start dialing any other
numberm, it is assumed to be local, and thus fixed length.  If you
start with a 0, then the 2nd digit is examined, and that determines
the length of the area code.

For example, is the 2nd digit is a 7, those area codes are all 4
digits (07??).

I am basing these statements on memory, so don't quote me as
authoritative.  Just something I noticed while living there.  If
someone living in Japan today, with more knowledge of Japanese
telophony could confirm or deny this, that would be great (my wife,
who's Japanese, had absolutely no clue, but then she's not a geek, and
doesn't understand why I find this even remotely interesting).

```