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Chapter 3 - Before You Deploy
© Polycom, Inc. 67
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).