Polycom ViewStation EX4000 - Manual (Page 92)

Integrators’ Reference Manual for ViewStation EX, ViewStation FX, and VS4000
82 www.polycom.com
You must use an external power supply if you use the internal CSU
capability of the PRI T1 network interface module.
Channel Service Unit
In North America, the PRI T1 network interface module can be
connected to an external Channel Service Unit (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. A CSU is normally used only when the PRI network
interface module is connected directly to a telephone company
switch, not a PBX.
Outside North America, CSUs are not used with PRI network
interface modules.
If you use an external CSU, connect an RJ-45 cable from the CPE
equipment side of the CSU to the PRI network interface module.
ADTRAN Atlas 800 Plus E1 Module
Firmware
If you are using an ADTRAN Atlas 800 Plus E1 Module, it must use
firmware version G03b or later.
Channel Restarts
Wait two to three minutes after the endpoint has been powered on
and the PRI status icon has turned green before making or receiving
calls with the ADTRAN Atlas 800 Plus. This allows time for channel
restarts on the ADTRAN Atlas 800 Plus E1 module. If you place a
call before channel restarts are complete, a Network Congestion
message appears on the system. Incoming calls during this time will
receive a Far Site Busy message.