for "User Reservation." Describes how to transport user defined bit streams between conferencing end-points. Part of the T.130 family. See DS-3. talking head The portion of a person that can be seen in the typical business-meeting-style videoconference; the head and shoulders. Because there is little motion in a talking head image (most is in facial expression) it is easy to capture with compressed video. In CATV systems the subscriber drop connects to feeder cables via taps; passive devices that isolate the feeder cable from the drop. tariff The terms and conditions of telecommunications or transmission service. Tariffs generally require approval by a regulatory body such as the FCC, PUCs or Often (UK). TCP/IP Transmission Control Protocol/Internet Protocol. A de facto standard and a set of internetworking protocols originally developed by the Department of Defense. Connects dissimilar computers across networks and is, therefore, widely used in the private sector. TCP/IP protocols work in the third and fourth layers of the OSI model to guarantee the delivery of data even in Video Communication: the Whole Picture very congested networks. Time Division Multiplexing. A technique for interleaving multiple voice, data and video signals onto a single carrier by assigning each signal its own separate time slot during which it can place a segment of its digitally-encoded transmission. At the distant end, the signals are separated SO that each discrete signal can be re-oriented and recombined as an entire communication or message. Telco A generic name generally used to refer to local exchange carriers; telephone companies providing local exchange service. telecommunications The art and science of applying services and technologies in order to enable communications over distance. Uses technologies such as radio, terrestrial and cable-based services, wireless transmission and optical fiber networks. Telecommunications Passed by the 104th Congress and signed by President Competition and Clinton in February, 1996, the Teleco