Nortel Networks 1000 - Manual (Page 43)

Line cards 43
attempt to use a Lineside T1 line, the system completes the call
termination. It does not back down and allow the CPE to complete the call
origination, as in normal ground start operation.
If both incoming and outgoing calls are to be handled through the Lineside
T1 interface, separate channels should be configured in the system and
the CPE for each call direction. This eliminates the possibility of glare
conditions on call origination.
Voice frequency audio level
The digital pad for Lineside T1 card audio level is fixed for all types of call
connection (0 dB insertion loss in both directions), and differs from the
analog line. Audio level adjustments, if required, must be made in the
Lineside T1 terminal equipment.
Off-premise line protection
Off-premise applications are installations where the telephone lines are
extended outside the building where the PBX system is housed, but the
lines are not connected to public access facilities. This application is
commonly referred to as a "campus installation."
In off-premise applications, special protection devices and grounding are
required to protect PBX and telephone components from any abnormal
conditions, such as lightning strikes and power line crosses.
The NT1R20 Off-Premise Station Line card has built-in protection against
lightning strikes and power line crosses. These should be the preferred
cards for an off-premise application. Other cards can be used when
external line protectors are installed.
When using the Lineside T1 card for an off-premise or network application,
external line protectors must be installed. Install an isolated type Channel
Service Unit (CSU) as part of the terminal equipment, to provide the
necessary isolation and outside line protection. The CSU should be an
FCC part 68 or CSA certified unit.
Line protectors
Line protectors are voltage-absorbing devices that are installed at the
cross-connect terminals at both the main building and the remote building.
The use of line protectors ensure that system and telephone components
are not damaged from accidental voltages that are within the limit of
the capacity of the protection device. Absolute protection from lightning
strikes and other stray voltages cannot be guaranteed, but the use of line
protection devices significantly reduces the possibility of damage.
Nortel Communication Server 1000
Circuit Card Reference
NN43001-311 02.06 Standard
27 August 2008
Copyright © 2003-2008 Nortel Networks
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