[asterisk-users] Asterisk as a call recorder for ISDN30 ?

[Michael Collins]

Mike,

First, what kind of T1 card(s) do you have?  (Just curious.)

I've seen two different theories of operation, although I have
experience only with one, and that's not with Asterisk.  One is a
passive tap, the other is a "pass-through."  I can't say that I know if
they work or how, but hopefully someone one the list can give you a
hint.

A passive tap looks something like this:

PSTN <---+---> PBX <---> LAN
         |
         |
         V
     Asterisk <---> LAN

We have this exact scenario with our call recording system, except that
we have a proprietary solution.  (Very expensive, very yucky, I wish I
had Asterisk available when we were looking for this solution... :(  )

I know this works, at least in theory, because that's what we're doing
right now.  What I don't know is whether or not the various T1 cards
that work with Asterisk can be configured for this scenario.
Essentially the call recorder device (Asterisk, in the above scenario)
is set up for inbound only communications.  I don't know what is done at
the hardware or device-driver level to configure the cards to work only
on the receive pair and not the transmit pair.  Also, the LAN connection
is just to illustrate the fact that you may need to have some sort of
on-line database to index the calls, e.g. "the call on channel 3 of span
2 at 11:19am was made by extension number 123..." In other words, it is
useful to have a correlation between the CDR from Asterisk and the CDR
from the PBX.  (This is a project in its own right.)


I've heard also of the pass-through scenario, which I imagine would look
like this:

PSTN <---> Asterisk <---> PBX

This scenario would require two Asterisk T1 ports for each span.
However, I'm guess that Asterisk and the dialplan could handle the
pass-through and call recording relatively easily given enough CPU
muscle and the fact that there wouldn't need to be any transcoding.  At
the very least the dialplan would have to handle inbound calls from the
PSTN and route them to the PBX accordingly, and it would, of course,
have to have some means of handling outbound calls from the PBX to the
PSTN.  I'll bet there are dialplan gurus out there who've done this sort
of thing already... If you have then we'd love to hear about it.  Please
let us know what hardware you used, how you did the dialplan, and what
challenges you had to overcome.

Thanks,
MC


> -----Original Message-----
> From: asterisk-users-bounces at lists.digium.com [mailto:asterisk-users-
> bounces at lists.digium.com] On Behalf Of Alex Balashov
> Sent: Tuesday, May 29, 2007 10:35 AM
> To: Asterisk Users Mailing List - Non-Commercial Discussion
> Subject: Re: [asterisk-users] Asterisk as a call recorder for ISDN30 ?
> 
> 
> Mike,
> 
> This thread might be of aid:
> 
>
http://www.mail-archive.com/asterisk-users@lists.digium.com/msg180994.ht
ml
> 
> -- Alex
> 
> On Tue, 29 May 2007, Mike Dent wrote:
> 
> > Hi,
> > would it be possible to use Asterisk to record calls only? There
would
> > be an existing PBX and calls come in on a ISDN30 line?
> > The Asterisk box would need to sit between the incoming ISDN 30
> > circuit and the existing PBX.
> > Is this possible?
> >
> > thanks
> > Mike
> > _______________________________________________
> > --Bandwidth and Colocation provided by Easynews.com --
> >
> > asterisk-users mailing list
> > To UNSUBSCRIBE or update options visit:
> >  http://lists.digium.com/mailman/listinfo/asterisk-users
> >
> 
> --
> Alex Balashov
> Evariste Systems
> Web    : http://www.evaristesys.com/
> Tel    : +1-678-954-0670
> Direct + +1-678-954-0671
> _______________________________________________
> --Bandwidth and Colocation provided by Easynews.com --
> 
> asterisk-users mailing list
> To UNSUBSCRIBE or update options visit:
>    http://lists.digium.com/mailman/listinfo/asterisk-users