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Glossary of broadband terminology: T

T-1

Roughly the US equivalent of E-1. This is a Bell system term for a digital carrier facility used for transmission of data through the telephone hierarchy at a transmission rate of 1.544 Mbps.

T-3

The US equivalent of an E-3. This is a Bell system term for adigital carrier facility used for transmission of data through the telephone hierarchy at a transmission rate of 45 Mbps.

Telco

A generic term for the local telephone company operator in a given area. In the US, the major telcos are the seven regional Bell operating companies and the leading independent telcos, GTE, SNET, and Sprint; in Europe, Asia, and elsewhere, the term "telco" generally refers to the incumbent monopoly, but increasingly refers to competing local providers as well.

Telephony over Passive Optical Network

Telephony using a PON as all or part of the transmission system between telephone switch and subscriber.

Telnet

A program that lets you connect to other computers on the Internet.

Time Division Multiplexing

Technique where data from multiple channels may be allocated bandwidth on a single wire pair based on time slot assignment.

Transmission Control Protocol/Internet Protocol

The protocols (TCP/IP) are the result of the Defense Advanced Research Projects Agency (DARPA) project to interconnect disparate computer networks of the 1970s. Today the protocols are the basis of the Internet.

Trellis Coding

A form of error correction found in many modems that allows for forward error correcting to account for bit errors from various interference on communications lines, such as cross talk and background noise.

Tunneling Protocol

A technology that enables one network to send its data via another network's connections. Tunneling works by encapsulating a network protocol within packets carried by the second network. For example, Microsoft's PPTP technology enables organizations to use the Internet to transmit data across a VPN. It does this by embedding its own network protocol within the TCP/IP packets carried by the Internet.

Twisted Pair

A common form of copper cabling used for telephony and data communications. It consists of two copper lines twisted around each other; the twisting protects the communications from electromagnetic frequency and radio frequency interference. See also Unshielded Twisted Pair.