Nortel Circuit Card 311 Reference page 159

A feature of many (though not all) standard telephones is that the loudness
increases with decreased current. So as the line (Meridian 1 to OPS
termination) facility gets longer and lossier, the increased loudness of the
telephone somewhat compensates for the higher loss, assuming direct
current feed from the PBX with constant voltage at the feeding bridge.
However, this compensation is not available when:
•
•
•
OPS line terminations with loudness characteristics designed for other
applications can also impact transmission performance. For example,
wireless portables loudness characteristics are selected for connections to
switching systems for wireless communication systems; if used in an OPS
arrangement without consideration for these characteristics, the result could
be a significant deviation from optimum loudness performance.
The loss plan for OPS connections is designed so that a connection with
an OPS termination provides satisfactory end-to-end listener volume when
the OPS termination is a standard telephone set. The listener volume
at the distant end depends on the OPS termination transmit loudness
characteristics; the volume at the OPS termination end depends on the
OPS termination receive loudness characteristics.
On some standard telephone sets, the loudness increases with decreased
current. As the line (PBX to OPS termination) facility gets longer and loss
increases, the increased loudness of the set compensates for the higher
loss, assuming direct current feed from the PBX with constant voltage at the
feeding bridge. This compensation is not available in the following situations:
•
•
•
OPS line terminations with loudness characteristics designed for other
applications can also impact transmission performance. For example,
wireless portables loudness characteristics are selected for connections to
switching systems for wireless communication systems; if deployed in an
OPS arrangement without due consideration for these characteristics, the
result could deviate significantly from optimum loudness performance.
Copyright © 2003-2008, Nortel Networks
.
the termination is a non-compensating telephone
the OPS port is served by a line card using a constant-current feeding
bridge
the OPS termination is to telephones behind a local switch providing
local current feed, such as a fax machine
when the termination is a non-compensating telephone set
when the OPS port is served by a line card using a constant-current
feeding bridge
when the OPS termination is to telephone sets behind a local switch
providing local current feed, such as a key telephone system
Nortel Communication Server 1000
Circuit Card Reference
NN43001-311 01.04 Standard
Release 5.0 23 May 2008
Application 159