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Glossary

Telecoms terms and abbreviations can be a little confusing, even for the most experienced engineers. Here’s a short glossary of some of the terms we use.

C

CAS
Channel Associated Signalling
Term given to protocols where dedicated channels are assigned to each traffic channel.
CCITT
Consultative Committee on International Telephone & Telegraph
This was the previous (before June 1994) for ITU-T
CCS
Common Channel Signalling
A mode of operation whereby the the signalling channel is used as a datalink to carry call control and management signals and is not dedicated to particular bearer channels in a fixed pattern.
CDMA
Code Division Multiple Access
“Under CDMA, communications channels are created by assigning a special coding scheme to information flows. CDMA-based second generation cellular radio systems are in use in parts of Asia and North and South America.”
CDSL
Customer Digital Subscriber Line
CGB
Circuit Group Blocking Message
CGU
Circuit Group Unblocking Message
CIC
Carrier Identification Code
The CIC is a number used by switches at each end of a point-to-point telephony circuit (controlled by ISUP or TUP) to identify a specific bearer channel. The bearer channel is typically a single time slot on a T-1/E-1 interface
CIDS
Calling Identity Delivery & Suppression
CLID
Calling Line ID
CLLI
Common Language Location Identification
CNAM
Calling NAMe - CNAM is an Intelligent Network service which allows delivery to the subscriber of the calling party number and a readable calling name in digital readout, identifying the caller to the called party.
COT
Continuity Test Message
CPG
Call Progress Message
CRA
Circuit Reservation Acknowledgement Message
CRC-4
Cyclic Redundancy Check
A method of checking for transmission errors in E1 trunk lines.
CRM
Circuit Reservation Message
CS-1
Capability Set 1
Refers to the SS7 Intelligent Network (IN) Standard ITU-T Intelligent Network CS-1 Standard
CSC
Circuit Supervision Control
CVR
Circuit Validation Response Message
CVT
Circuit Validation Test Message