U
- UAC (User Access Control)
- UAC (User Agent Client)
- UAS (User Agent Server)
- UC (Unified Communications)
- UDP (User Datagram Protocol)
- UHF (Ultra High Frequency)
- UMTS (Universal Mobile Telecommunications System)
- Unconditional Forwarding
- Unicast
- Unified Communication as a Service (UCaaS)
- Unified Messaging
- Unified Threat Management (UTM)
- Universal Service Fund (USF)
- Update
- Uplink
- UPS (Uninterruptible Power Supply)
- Upstream
- Uptime
- Uptime Guarantee
- URI (Uniform Resource Identifier)
- URL (Uniform Resource Locator)
- Usability
- Usage Policy
- Usage Report
- USB (Universal Serial Bus)
- User Agent
- User Agent Client (UAC)
- User Agent Server (UAS)
- User Datagram Protocol (UDP)
- User Experience (UX)
- User Profile
- Username
