| Abbreviation | Definition |
|---|---|
| CCTN | Clear Channel Traffic Network (Clear Channel Albany; New York) |
| CCTS | Commission for Complaints for Telecom-television Services |
| CCTS | Commissioner for Complaints for Telecommunications Services |
| CCTV | Closed-circuit television |
| CD | Carrier Detect |
| CD | Channel Delay |
| CD | Connect Direct |
| CDA | Communications Decency Act of 1996 |
| CDM | Code Division Multiplexing |
| CDMA | Code Division Multiple Access |
| CDN | Control Directory Number |
| CDO | Community Dial Office |
| CDR | Call Detail Record |
| CDR | Clock and Data Recovery |
| CDSL | Consumer Digital Subscriber Line |
| CELL | Caller Enabled Leased Line |
| CEP | Communication End Point |
| CEPT | Committee of European Postal & Telephone (authorities) |
| CEPT | Committee of European Postal & Telephone Authorities |
| CES | Circuit Emulation Service |