[Asterisk-Users] How to number extensions - Which way is best?

[Tim Burt]

If this topic has been discussed already, please point me to it.  I have
looked, and I don't see any discussion in the past couple of months or in
the wiki.

When setting up your inside extensions, it can be helpful to choose the
numbering carefully.  Ideally, you would like it to not conflict with the
dialing of an outside number.

For example, the extension...

1212

Is very similar to dialing a new york long distance number:

1-212-555.1212

The phone company intentionally avoids some number combinations.  Local
numbers never start with a "1".  This way, the Phone company switch knows
that any number that starts with a "1" needs long distance routing.

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Some switch systems avoid this issue by requiring that extensions dial a 9
to get an outside number.  This allows the use of any extension numbers
internally, as long as they do not begin with a "9"!

I can setup asterisk to work this way.

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What would be a wise choice for your extension numbering if you were just
setting up a new system?

Is there a "better to use" set of extensions, that avoids confusion with
dialing of external numbers.

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Or perhaps, I am way off base.  Does asterisk have some magic sauce that
makes this a moot issue?

Thanks in advance.