Polycom EX Guía De Referencia
Chapter 2 - Setting Up Your System Hardware
© Polycom, Inc.
2-13
PRI Network Interface Module
The PRI network interface module allows you to make ISDN calls using a PRI line.
You may need one of these items in addition to the PRI network interface module
and the items provided with it:
and the items provided with it:
❑
External Channel Service Unit (CSU)
— If you connect a PRI T1 network
interface module outside a PBX, you may wish to connect it through a CSU.
The CSU isolates the PRI from the network, and continues to transmit a signal
to the network even if the PRI network interface module loses power or is
disconnected. This prevents the line from being deactivated. CSUs are used
only in North America.
The CSU isolates the PRI from the network, and continues to transmit a signal
to the network even if the PRI network interface module loses power or is
disconnected. This prevents the line from being deactivated. CSUs are used
only in North America.
❑
PBX crossover cable —
An RJ-45 crossover cable may be required when
connecting the PRI network interface module to a PBX or other third-party
network access device.
network access device.
❑
75 Ω coaxial adapter —
The PRI E1 line termination is 120 Ω. In some areas,
however, the E1 network connection is via a 75 Ω coaxial cable. The PRI
network interface module does not directly support this, but you can obtain
passive adapter devices from various vendors.
network interface module does not directly support this, but you can obtain
passive adapter devices from various vendors.