Chapter 3 - Before You Deploy
© Polycom, Inc. 65
The PRI direct from the telephone service provider should support
both data and voice for Polycom’s voice add-on capability of
systems.
Determining Usage
To get the best rate of return from PR I lines, they sho uld be used as
much as possible. To do this, look at the data and video traffic as a
whole. Establish a reasonable ratio between the total bandwidth
required if every device is in use and the number of lines provided.
A ratio of 10:1 is fair for general use. If you use a PBX, access switch,
or other data communications unit, the total number of lines into
your customer premise equipment (CPE) can be allocated by
channel to your equipment, according to the bandwidth required at
any given time.
PBX Network Configuration
The PBX or other CPE that will be providing the ISDN PRI interface
to the system must be able to provide a clock signal.
Other than the clocking requirement, the rest of the ISDN PRI
provisioning on the PBX is very similar to what would be requested
of an outside ISDN provider.
ISDN BRIAll 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.
NT1 Devices that you may order through Polycom:
❑Single NT1 (2200-08406-001 or NT1)
❑Triple NT1 (2200-08406-003)
❑Quad NT1 (2200-08406-004 or NT1-QUAD)