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Administrator’s Guide for ViewStation EX, ViewStation FX, and VS4000
A-4 www.polycom.com/videodocumentation
ISDN BRI
All Polycom ISDN BRI interfaces are S/T-loop. ISDN BRI lines coming direct from
a Telco are U-loop, so if your system is not behind a PBX or other private network,
you must connect the BRI interface to BRI line(s) through an NT1 device capable
of supporting multiple BRI lines.
For ISDN BRI lines to be used from a PBX to a videoconferencing system, you must
do these things in addition to meeting the other requirements.
❑ Determine the interface type of the ISDN BRI network module in the PBX
(U-loop or S/T-loop). This will determine whether or not you need an NT1
device between the PBX and the ISDN BRI interface of the videoconferencing
system.
❑ If the ISDN BRI network module in the PBX is S/T-loop, there is a 500-foot
limitation with S/T-loop ISDN. The module may still require a special jack
with a resistor.
❑ Ensure that the ISDN PRI or multiple BRI lines, on the public side (from the
Telco) are provisioned to carry data traffic as if it was connected directly to the
videoconferencing systems as discussed in the appropriate sections above.
Voice can be added but is not required. Items such as switch protocol,
numbering plans, etc. are not necessary as those are determined by the PBX
connecting to the ISDN lines from the Telco side.
❑ Ensure that the ISDN BRI lines’ channels that connect to the videoconferencing
systems are mapped appropriately to the channels on the public network side
of the PBX that connects to the Telco’s ISDN cloud. This is critical also for the
success of the inbound calls from systems outside the company to ensure that
the ISDN number, provided to the videoconferencing system by the PBX, is
routable in the public ISDN cloud and through the PBX to the appropriate
videoconferencing system.
❑ The ISDN BRI lines between the PBX or other CPE and the videoconferencing
system(s) should be provisioned in the same way as ISDN BRI lines that would
be connected the system(s) directly from a Telco, as described below.
The following requirements are common to all BRI deployments.
❑ ISDN BRI lines need to be configured in the same way as one of the following
two Bell Core equivalents:
Capability Package R: Circuit Switched Data on 2 B channels. Data capabilities
include Calling Number Identification. No voice capabilities are provided.
Capability Package S (recommended if system is not behind a PBX): Alternate
Voice/Circuit Switched Data on 2 B channels. Data and voice capabilities
include Calling Number Identification.
❑ Both B channels must carry circuit-switched videoconferencing data (voice can
be added but is not required).