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MERLIN LEGEND Communications System Release 6.1
Network Reference
555-661-150
Issue 1
August 1998
Glossary
Page GL-6
centralized
telephone
programming
Programming of features on individual telephones;
performed at a central location by the system manager.
See also
system programming
and
extension
programming.
central office See
CO
.
Centrex Set of system features to which a user can subscribe on
telephone trunks from the local telephone company.
channel Telecommunications transmission path for voice and/or
data.
channel service
unit
See
CSU
.
checksum Sum of ones in a sequence of ones and zeros used to
detect or correct errors in data transmission.
circuit-switched
data call
Data call made through an exclusively established and
maintained connection between
data stations
.
class of restriction See
COR
.
clear data channel Clear data channels (also called unrestricted data
channels) allow the transmission of occurrences of more
than seven contiguous zero bits. If a clear data channel is
requested and only restricted channels are available, the
call will be rejected. See also restricted data channel.
clock
synchronization
When digital signals are transmitted over a
communications link, the receiving end must be
synchronized with the transmitting end to receive the digital
signals without errors using clock synchronization. A
system synchronizes itself by extracting a timing signal
from an incoming digital stream. All the digital facilities in a
network operate from a single common clock, preferably a
port connected to a digital
PSTN
facility on a
hub system
or
a system that connects two network systems. In this case,
all digital facilities specify a loop clock source. One system
in a network may be specified as a local clock source when
no functioning digital facility in the network is connected to
the
PSTN.
All other digital facilities then use this clock and
specify their clock sources as loop. Primary, secondary,
and tertiary clock sources are specified to allow backup
synchronization in the event that the primary source is out
of service.
CMS (Call Management System) DOS-based application that
simulates the actions of a system operator by answering
and distributing calls. Also produces reports for call
analysis.
CO (central office) Location of telephone switching equipment
that provides local telephone service and access to toll
facilities for long-distance calling.
coaxial cable Cable consisting of one conductor, usually a small copper
tube or wire within and insulated from another conductor of
larger diameter, usually copper tubing or copper braid.