[Asterisk-Users] SIP Video Conferencing System to PRI

[Gil Kloepfer]

I have a Polycom VX7000 video conferencing system (VTC) on loan that
has SIP capability.  What I'm trying to do is:

    ISDN PRI -(Digium Quad T1)-> Asterisk -(net)-> VX7000

    If someone calls on the number for the video conferencing system,
    the Asterisk server forwards the call over SIP to the VX7000.

I also have another Polycom VTC that uses 3 ISDN BRIs and am trying to
call the VX7000 from that VTC.

It doesn't work.  What happens is that the VX7000 appears to answer
the SIP call, but the BRI-based VTC doesn't ever see the call as
completed successfully.

When I do a pri debug on the span from the Asterisk box, there is a
"User Information Layer 1" of type Unknown (4)...and also, there is an
ISDN message sent that the call is no longer end-to-end ISDN.  I think
both of these may have something to do with the problem.

I suspect that the problem here is somehow translating the ISDN PRI
"information type 4" to the proper SIP RTP stream type, but I don't know
for sure.

Has anyone done this successfully before and can give me some pointers
as to how this would get configured?  For reference, here is the
pertinent config file stuff:

(in sip.conf)
     [4910]
     type=friend
     secret={hidden}
     host={also-hidden}
     nat=no
     canreinvite=no
     allow=all
     videosupport=yes

(in zapata.conf)
     signalling=pri_cpe
     switchtype=ni1
     usecallerid=yes
     hidecallerid=no
     usecallingpres=yes
     echocancel=yes
     echocancelwhenbridged=no
     busydetect=no
     immediate=no
     context=sbc-0074-incoming
     group=1
     channel => 1-23

(in extensions.conf)
     [sbc-0074-incoming]
     exten => {number hidden},1,Dial(SIP/4910)

Thanks in advance for your help.  If you'd like to take the discussion
off the list, you can contact me at vtcinfo at kloepfer.org (temporary e-mail
address).

---
Gil Kloepfer