Glossary
CCITT
Consultative Committee on International Telephony and Telegraphy. A body of the International Telegraph Union (ITU) which prepares recommendations, com- monly referred to as international standards, to resolve technical telegraph and telephone problems.
central office (CO)
In telephony, the facility housing the switching system and related equipment that provides telephone service for customers in the immediate geographical area.
circuit mode
Type of switching that assigns a call to a specific circuit path. The circuit is not shared with other calls.
clear channel
A channel in which all the 64 kbps are used for transmission. To achieve this, bit robbing signalling must be eliminated. (NOTE: Not to be confused with clear chan- nel protocol.)
common channel interoffice signalling (CCIS)
A signalling system developed for use between stored program switching systems. All of the signalling information for a group of trunks is transmitted over a dedi- cated
CPE
Customer premises equipment. A generic term for communications terminal gear owned by the customer, residing on customer premises.
CSU
Channel service unit. A component of CPE used to terminate a digital circuit, such as DDS or T1 at the customer site. Performs certain
The ISDN channel that carrier signalling information to control the call setup, tear- down, or invocation of supplementary services. The
DCE
data communications equipment. The portion of a data terminal that provides the interface to the network.
138 | ISU 2x64 Dual Port ISDN Service Unit User Manual |
