Graham,
I think that this depends on a couple of things. The type of PBX you're
connecting with and what type of connection will exist between your PBX and
asterisk.
I think you've correctly identified the challenge: How do we get the number
of the extension that was dialed originally?
If you're interconnecting with analog lines, I can't see any way to make it
work practically for more than a couple of users. If you're using a digital
connection like T1 PRI, then you might have a chance.
I see a few potential solutions. All of them are subject to the capability
and cooperativeness of your PBX.
1) Setup asterisk as a trunk group IE "Dial 9 for outside, Dial 8 for
asterisk"
I've done this in the past with an Avaya G3 for purposes other than
voicemail. PBX users dial 8 followed by the asterisk extension. You could
use this in your scenario by programming extension 201 to forward to 8201 if
not answered within x rings. You'll usually have to allow users to forward
to off premise numbers. This creates a bit of a security issue in that a
user could forward their phone to a long distance number and take advantage
of it or cause toll fraud.
2) Setup extensions on asterisk for each user: "User 201 has voicemailbox
301"
This is similar to the above but it takes up space and stations in your PBX
dialplan. You could just create stations on the PBX that point to asterisk
and forward voicemail calls to those extensions.
3) Use Redirecting DNIS (RDNIS) to determine the number originally dialed.
This is theoretically possible but not likely to work in my opinion. I'm
not sure if your PBX has implemented RDNIS in a way that asterisk will read
it. It has the advantage of you only needing 1 extension pointing to
asterisk which will handle all your voicemail needs. Here's the idea
though: When the call is sent to user 201, the DNIS is 201. When that call
goes CFNA (call forward no answer) to your asterisk voicemail extension (say
700) use voicemail(${RDNIS}) to send the caller to the correct mailbox.
Here's a good link on RDNIS: http://www.voip-info.org/wiki/view/RDNIS
I notice that there's some reference to RDNIS in SIP so maybe you could get
away with that instead of PRI.
It's an interesting idea you've got. Keep us posted on your progress. I'd
also be interested to know which switch you're using. If it's an Avaya
product, I may be able to offer some specific advice there. I don't know
much about Nortel PBXs except that I've been frustrated by them.
Dave
On 1/31/06, Graham Todd < [EMAIL PROTECTED]> wrote:
>
> == Automatic recognition of call origin and pass thru to a voicemail box
> ==
>
> This query has more to do with an issues of "stealth" introduction of
> */PBX to
> "complement" an existing system than with a asterisk issue per se ...
>
> Someone asked me if they could set their phone to forward calls to an
> Asterisk
> server plugged into an extension on the existing PBX. Forwarded messages
> would
> get recorded/saved on * and then e-mailed to them instead of being saved
> on
> the current PBX (which either doesn't have this feature or doesn't have it
>
> turned on).
>
> Can I get Asterisk to automatically recognize incoming calls by their
> extension number on the foreign PBX and to associate the calls with one of
> its
> own voice mailboxes? Is this easily done?
>
> Since the forwarded calls would come from another extension on the current
> PBX, I guess what I want is LookupCIDName() to associate the forwarded
> call
> with the extension number that **received** it from the outside; and then
> to
> store the message in the Asterisk vmailbox that I would create for each of
> the
> foreign PBX extensions. I am having trouble working things out. Perhaps
> because:
>
> - when forwarding the existing PBX strips CID info;
> - the CID info comes from the external call and not the foreign PBX
> extension
> - some other random switch needs to be flipped on the existing PBX
>
> Are other folks doing this? Am I on the right track? :)
>
> Thanks for any ideas.
>
>
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--
David Donovan
Consultant
Fulcrum Solutions
