Overview Page 55 of 894

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 will 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.

Circuit Card Description and Installation

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Nortel Networks 553-3001-211 manual Voice frequency audio level, Off-premise line protection, Line protectors
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