| Abbreviation | Definition |
|---|---|
| UIS | User Interface Services |
| UIS | User Interface System |
| UKERNA | UK Education and Research Networking Association |
| ULA | Universal LAN (Local Area Network) Address |
| ULC | Ultra Light Client |
| ULC | Uplink LAN (Local Area Network) Creator |
| ULC | Uplink LAN Center |
| ULH | Ultra-Long Haul |
| ULLS | Unconditioned Local Loop Services |
| ULS | User Locator Server |
| ULU | Unicode Little Unmarked |
| UM | Unified Messaging |
| UMA | Unified Messaging Application |
| UMV | Unique Monthly Views |
| UMWI | Unprocessed Message Waiting Indicator |
| UNA | UNA Networking Applications |
| UNA | Uniqueness of Names Assumption |
| UNA | United Networking Applications |
| UNC | Uniform Network Controller |
| UNC | Universal Network Command |