asterisk users - Feb 2005 - How to number extensions - Which way is best?

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.

------------------

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.

------------------

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.

------------------

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

Thanks in advance.

I'd say, consider your audience (user-base) and let common sense
prevail.

If your user-base is accustomed to business PBXs, they'll already expect
to have to dial a 9 or 7 to "get out".  In that case, number your
extensions any way you like, must avoid that "outside" digit.

Personally, I prefer a "transparent" PBX, and this is my setup:

011... - International calls
1... - NANPA calls
2... - internal extensions
3... - external extensions (SIP/IAX clients)
411 - operator
6... - speed dial
8... - direct trunk access (in my case -- all IAX --, that means it will
set the proper caller-id for outgoing calls)
911 - guess that that's for.

The advantage here is that incoming calls can generally be returned
without any digit-magic, just by selecting a number from the incoming
call-list and pushing Redial or what have you.  Since I use multiple
providers, I have an agi script that "normalizes" this number for me
(http://muware.com/asterisk)

If you have a T1 with a thousand-block of DIDs, I'd recommend
coordinating the extension with the DID#, such that -- 800-555-1234
corresponds to extension 2-1234, and 800-555-4637 can be dialed as
2-4637 internally.  Ditto for voice-mail.

And whatever you decide, make sure that 911 is idiot proof -- allow
calling as 911, 7911, 9911, etc.
> -----Original Message-----
> From: Tim Burt [mailto:asterisk-list@timburt.com] 
> Sent: Monday, February 07, 2005 4:46 PM
> To: asterisk-users@lists.digium.com
> Subject: [Asterisk-Users] How to number extensions - Which 
> way is best?
> 
> 
> 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.
> 
> ------------------
> 
> 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.
> 
> ------------------
> 
> 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.
> 
> ------------------
> 
> Or perhaps, I am way off base.  Does asterisk have some magic 
> sauce that makes this a moot issue?
> 
> Thanks in advance. _______________________________________________
> Asterisk-Users mailing list
> Asterisk-Users@lists.digium.com 
> http://lists.digium.com/mailman/listinfo/aster> isk-users
> To 
> UNSUBSCRIBE or update options visit:
>    
http://lists.digium.com/mailman/listinfo/asterisk-users

Combing thru the Wiki, I did find that Asterisk does have some secret
sauce with respect to sorting out what the caller is dialing...

It is covered in the wiki page "Asterisk Extension Mapping"

http://www.voip-info.org/tiki-index.php?page=Asterisk+Extension+Matching

This page does an excellent job of explaining the intuitive logic that
Asterisk uses to determine when you are dialing an extension or dialing an
outside number.

To followup on the excellent suggestions thus far, I have concluded...

1) For an office environment, where dialing "9" for an outside line is
not
uncommon, the "dial 9" option may make sense for a cleaner
implementation.

2) For a home (or small office) environment, where nobody expects to have
to dial a "9", it is better to rely on the Asterisk Extension Mapping
logic.

PLUS...
Numbering your extensions in the "100" to "119" range (or
for larger
environments 1000 to 1199) will provide the cleanest interface.  This is
because a leading 1 indicates a long distance call, and the number
following a leading 1 cannot be a "0" or a "1" for long
distance.
Therefore, asterisk can determine with the second digit dialed that you
are dialing an extension, and not a long distance number.

Anyone have any comments on the above suggestions?
> 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.
>
> ------------------
>
> 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.
>
> ------------------
>
> 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.
>
> ------------------
>
> Or perhaps, I am way off base.  Does asterisk have some magic sauce that
makes this a moot issue?
>
> Thanks in advance.
> _______________________________________________
> Asterisk-Users mailing list
> Asterisk-Users@lists.digium.com
> http://lists.digium.com/mailman/listinfo/asterisk-users
> To UNSUBSCRIBE or update options visit:
>    http://lists.digium.com/mailman/listinfo/asterisk-users
>