Shane Spencer wrote:
I am trying to do a wire level tap on T1 equipment using digum
equipment. So far most call monitoring hardware for call centers try
to stay on the analog side requiring a lot of rewiring. I have
already posted to the list about T1 "bridging" using DAC's support in
the zaptel drivers. I still don't know if I can spy on channel
information since I don't have any digium hardware on me until the
project begins.
There are a number of systems using ISDN digital taps. The proper way
requires a high impedance bridge - you don't want to load the line that
you're tapping.
Anybody found a method of spying on a D-Channel and all voice channels
using standard T1 equipment? I am making a rough assumption that if I
can trick the zaptel drivers into operating without anything
responding to a TX signal then I can do the following:
You can directly bridge the 2 ports and extract what you need as you
bridge - see pridump.c in libpri. You don't even need asterisk, just the
zaptel and libpri. The only problem with this approach, is that the
bridge becomes a point of failure. Your box down, your PRI goes down as
well.
S-T1 = T1 to Spy On
T1-1 = Digium T1 card #1
T1-2 = Digium T1 card #2
Map S-T1(RX) to T1-1(RX) and S-T1(TX) to T1-2(RX) and decode the
D-Channel where appropriate, should I be able to spy on the RX/TX
channels enough to make a recording including CID information? This
would help in situations where the monitoring system needs to be
replaced or taken down without bothering in-progress calls.
This is technically correct, but I don't know how well it works. Eicon
recommends a similar technique to do monitoring with their Eicon Server
cards. For the BRI, it's done this way. But for the PRI card, they
actually suggest using a custom cable. Eicon cards have a special Hi-Z
monitoring mode to support this application.
http://www.eicon.com/worldwide/solutions/How_To_Call_Tapping_and_Monitoring_with_Diva_Server
FYI, Voicetronix has a Hi-Z version of their OpenPRI card that work with
an open-sourced voice logging application available from their site.
Leo
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