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Description
553-3001-105
Standard 5.00
June 1999
Glare restrictions
In telephone lines or trunks, glare occurs when a call
origination attempt results in the answering of a terminating call that is being
presented by the far end simultaneously with the call origination attempt by
the near end.
The line-side T1 detects presentation of a terminating call (outgoing to
line-side T1 terminal equipment) by detecting ringing voltage. If application
of the ringing voltage is delayed due to traffic volume and ringing generator
capacity overload, the line-side T1 ground start operation cannot connect the
tip side to ground to indicate the line has been seized by the Meridian 1.
In ground start mode, glare conditions need to be considered if both incoming
and outgoing calls to the CPE equipment are going to be encountered. In the
event that both the Meridian 1 and the CPE equipment simultaneously
attempt to use a line-side T1 line, the Meridian 1 will complete the call
termination rather than backing down and allowing the CPE equipment to
complete the call origination, as in normal ground start operation. If both
incoming and outgoing calls are to be handled through the line-side T1
interface, separate channels should be configured in the Meridian 1 system
and the CPE equipment for each call direction, to eliminate the possibility of
glare conditions on call origination.
Voice frequency audio level
The digital pad for line-side T1 card audio level is fixed for all types of call
connection (0 dB insertion loss in both directions), and differs from the
Meridian 1 analog line. Audio level adjustments, if required, must be made in
the line-side 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 that might occur. Abnormal conditions include, but are not limited
to, lightning strikes and power line crosses.
Summary of Contents for NT1R20
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Page 154: ...Page 130 of 290 NT5D11 Line side T1 Interface Card 553 3001 105 Standard 5 00 June 1999 ...
Page 276: ...Page 252 of 290 QPC452 Basic 500 2500 Analog Line Card 553 3001 105 Standard 5 00 June 1999 ...
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