| Abbreviation | Definition |
|---|---|
| CPS | Customer Premises System |
| CPT | Cellular Paging Teleservice |
| CR | Call Reference |
| CRA | Constant Rate Allocation |
| CRACK | Challenge Response for Authenticated Crypto Keys |
| CRBT | Caller Ring Back Tone |
| CRBT | Color Ring Back Tone |
| CRC | Cyclic Redundancy Check |
| CRCDN | Call Redirection or Call Deflection Notification |
| CRIS | Carrier Route Information System |
| CRT | Combined Rlogin and Telnet |
| CRV | Call Reference Value |
| CS | Cable Select |
| CS | Carrier Sense |
| CS | Central Station |
| CS | Clear to Send |
| CS | Communications Satellite |
| CSA | Central Service Area |
| CSAA | Central Service Area Authority |
| CSAP | Core Service Access Point |