Polycom VS4000 manual PRI Network Interface Module

Chapter 2 - Setting Up Your System Hardware

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:

❑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.

❑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.

❑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.

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