asterisk users - Sep 2005 - Asterisk for "Man-In-The-Middle" Trunk Side Call Recording?

[Cross-posted to the asterisk forums, so if it seems familiar...]

My company is looking to implement 100% recording of inbound and outbound
calls. We're pondering using Asterisk as a trunk-side monitoring system
sitting between our Avaya Definity switch and our mixed bag of 6 T1 and PRI
circuits. I've read with interest Matt Roth's thread on the Asterisk
mailing
list, however, since his experience is recording SIP-SIP calls, I'm not sure
how applicable it is to our situation. The use of a RAM disk to buffer the
calls does seem like a great idea, however, I'm concerned that a single
server might not be able to handle the load of 12 T1 ports (6 outbound, 6
connected to the switch). I also understand there might be interrupt issues
with three Digium cards in a single box.

With that in mind, I have two ideas for implementing asterisk as a call
recording solution.

The first solution I call the single-box solution and involves a dual CPU
Xeon server (most likely a Dell PowerEdge 2800, 2850, or similar) with a
large amount of RAM and RAID-1 SCSI setup. We would add three TE411P or
TE410P cards and implement something similar to Matt Roth's setup, but on a
smaller scale.

The second solution involves using either three or six desktop type or 1U
computers with a single CPU, IDE disk, and 512-1GB of RAM. We would record
directly to disk and each box would only serve 1 or 2 outbound T1's (so, 2
or 4 T1's per machine). If we implemented this as a three-box solution, we
would use a single TE411P or TE410P card per server, if implemented using
six boxes, we would use TE210P cards.

My questions about this are:

1. Is this possible? Can Asterisk serve as a man-in-the-middle between a
traditional PBX and the telco loops?

2. If it's possible, which of the two possibilities above is better? For us,
rack space and power should not be an issue, we're interested in what will
be most workable.

3. Once you have the calls recorded, how do you access them? Is it possible
to use asterisk's logs to correlate calls recordings with specific
information? We're willing to do some custom programming here if need be.

4. Has anyone done anything like this before? If so, would you be interested
in a consulting gig?

Thanks in advance for your responses!

>
> 1. Is this possible? Can Asterisk serve as a man-in-the-middle  
> between a
> traditional PBX and the telco loops?
Yes,  Asterisk can be a PRI client to the telco and a PRI server to  
your internal PBX
>
> 2. If it's possible, which of the two possibilities above is  
> better? For us,
> rack space and power should not be an issue, we're interested in  
> what will
> be most workable.
I would go for multiple low end servers handling 1 or 2 T1s at a  
time.  You have g.711 coming in and going out so recording in g.711  
won't be too CPU intensive.  23 voice calls at 64kbps would be  
2.944mbps  (23 ^* 64000 * 2) so you'll need a hard drive/filesystem  
that can sustain at least 3mbps writes per T1 in the machine.
>
> 3. Once you have the calls recorded, how do you access them? Is it  
> possible
> to use asterisk's logs to correlate calls recordings with specific
> information? We're willing to do some custom programming here if  
> need be.
You should be able to tie the cdr information stored in a mysql  
database with the .wav file of the recording.  It is all setup in the  
extensions.conf file so you can choose the recording naming scheme  
there and make it work.  You would probably need to develop a web  
based app to handle the front end stuf.
>
> 4. Has anyone done anything like this before? If so, would you be  
> interested
> in a consulting gig?
I haven't.

One thing to watch out for is the new digium T1 cards that can bridge  
bearer traffic in firmware.  If that happens the voice doesn't leave  
the card and may not be recordable.  I'm not sure how Asterisk would  
handle that.
>
> Thanks in advance for your responses!
>
>
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On 09/30/05 03:12 Verlin Henderson said the following:
> Xeon server (most likely a Dell PowerEdge 2800, 2850, or similar) with a
> large amount of RAM and RAID-1 SCSI setup. We would add three TE411P or
> TE410P cards and implement something similar to Matt Roth's setup, but
on a
> smaller scale.
has the limit on 254 zap channels per server been removed ? admittedly, i 
may have missed the change where this occured, but it's certainly there in 
zaptel from a few months back.

-- 
Regards,                           /\_/\   "All dogs go to heaven."
dinesh@alphaque.com                (0 0)    http://www.alphaque.com/
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