Specifications

CL
Connectionless Service
CPE
Customer Premises Equipment
CODEC
COder/DECoder (a device that encodes and decodes signals)
companding
Non-linear reduction of a signal, usually compressing the larger signal values
CRC
Cyclic Redundancy Check
CRC-4
CRC using four check bits
CRC-6
CRC using six check bits
CSA
Carrier Serving Area
CSC
Common Signaling Channel
CSU
Channel Service Unit, an interface to a T1 line that terminates the local loop.
CTE
Channel Terminating Equipment (Network)
CTS
Clear To Send, a lead on an interface indicating that the DCE is ready to receive data.