Avaya MERLIN MAGIX Maintenance And Troubleshooting Manual page 275

Maintenance and Troubleshooting
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
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
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
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.
CO
Central
telephone service and access to toll facilities for long-distance calling.
GL-8
Data Stations.
Restricted Data
PSTN facility on a Hub System
Office. Location of telephone switching equipment that provides local
Channel.
or a system that connects two network