| Abbreviation | Definition |
|---|---|
| TDSP | Time Dependent Shortest Path |
| TE | Termination Enable |
| TE | Traffic Engineering |
| TE | Trunk Encryption |
| TED | Travelling Electronic Documentation |
| TEKF | Tangent Extended Kalman Filter |
| TEL | Traffic Event Logger |
| TELNET | TELecommunications NETwork |
| TEOS | Trusted E-mail Open Standard |
| TEP | Transport End Point |
| TES | Trans European System |
| TESS | Total Enterprise Security Service |
| TFS | Transfer File System |
| TFTP | Trivial File Transfer Protocol |
| TG | Trunk Group |
| TGD | Time / Group Delay |
| TGIS | Thames Global Internet Services |
| TGNP | Tanzania Gender Networking Programme |
| THG | Ten Hundred Gigabit |
| THK | TeleHallintoKeskus ( Finnish:Telecommunications Administration Centre) |