Single Mode Fiber - A fiber having a small core diameter and in which only one mode will propagate at the wavelengths of interest.
Synchronous Optical Network (SONET) - SONET is a Bellcore specification currently used in worldwide public data networks (PDNs). It defines a synchronous optical network-based user-network interface (UNI), either public or private, operating at speeds from 51 Mbps to 2 Gbps over single-mode optical fiber.

T1 - A digital transmission link with a capacity of 1.544 Mbit/s, used in North America. Typically channelized into 24 DS0s, each capable of carrying a single voice conversation or data stream. Uses two pairs of twisted pair wires.
T3 - A digital transmission link with a capacity of 45 Mbps, or 28 T1 lines.
Telco - Telephone company.
Telecommunications Industries Association - The group responsible for setting telecommunications standards in the United States.
Terabit - One trillion bits.
Transmitter - In fiber optic communications, a light source whose beam can be modulated and sent along an optical fiber, and the electronics that support it.
Twisted Pair - Relatively low-speed transmission medium consisting of two insulated wires - shielded or unshielded-in regular spiral patterns. The wires are twisted around each other to minimize interference from other twisted pairs in the cable. Twisted pair is common in telephone wiring and is increasingly common in data networks. Other high-speed forms of cable include coaxial and fiber optic cables.
Twisted-pair Cable - A cable consisting of four or more copper wires twisted together in pairs. Telephone wiring is an example of twisted-pair cable. Twisted-pair cable can be shielded or unshielded.

URL - Uniform resource locator. The address of a file (resource) accessible on the Internet. The type of resource depends on the Internet application protocol. For the World Wide Web's protocol, the Hypertext Transfer Protocol (HTTP), the resource can be an HTML page, a program such as a Java applet, or any other file supported by HTTP. The URL contains the name of the protocol required to access the resource, a domain name that identifies a specific computer on the Internet, and, if necessary, a path to the resource on the computer. The URL for Pavletich Electric & Communications, for example, is
http://www.pavelectric.com