T
- T1 Line
- T1 Multiplexer
- T1/E1 Interface
- T3 Line
- Tagging
- Tandem Switch
- TAPI (Telephony Application Programming Interface)
- TCP (Transmission Control Protocol)
- TDM (Time Division Multiplexing)
- TDM Switch
- Telecom Audit
- Telecom Expense Management (TEM)
- Telecom Regulatory Authority
- Telecommunication Network
- Telecommunications
- Telecommunications Closet
- Telecommunications Management Network (TMN)
- Telecommuting
- Teleconference
- Telemarketing
- Telemetry
- Telephone Consumer Protection Act (TCPA)
- Telephone Exchange
- Telephone Number Mapping (ENUM)
- Telephone Relay Service (TRS)
- Telephone System
- Telephony
- Telephony Application Programming Interface (TAPI)
- Telephony Gateway
- Telephony Service Provider
- Telepresence
- Telepresence Room
- Tenant Partitioning
- Terminal Adapter (TA)
- Test Access Point (TAP)
- Test Call Generator (TCG)
- Test Tone
- Text Messaging
- Text Relay
- Text-to-911
- Text-to-Speech (TTS)
- TFTP (Trivial File Transfer Protocol)
- Threshold
- Throughput
- Time Division Multiple Access (TDMA)
- Time Slot
- Time Synchronization
- Time to Live (TTL)
- Time-of-Day Routing
- TLS (Transport Layer Security)
- Token Bucket
- Token Passing
- Token Ring
- Token Ring Network
- Toll Billing
- Toll Fraud
- Toll Restriction
- Toll Ticketing
- Toll-Free Number
- Toll-Free Service
- Tone Dialing
- Topology
- Traceroute
- Traffic Analysis
- Traffic Analysis Tool
- Traffic Engineering
- Traffic Management
- Traffic Matrix
- Traffic Monitoring
- Traffic Monitoring System
- Traffic Policing
- Traffic Priority
- Traffic Shaping
- Traffic Simulation
- Transceiver
- Transcoder
- Transcoding
- Transcoding Gateway
- Transmission Control Protocol (TCP)
- Transmission Line
- Transmission Medium
- Transmitter
- Transport Protocol
- Trunk
- Trunk Group
- Trunk Line
- Trunk Port
- Trunk Reservation
- Trunking Gateway
- Tunneling Protocol
- Twisted Pair
