ADTRAN ISU 2X64 user manual 2B+D

Glossary

2B+D

The basic rate interface (BRI) in ISDN. A single ISDN circuit divided into two 64 kbps digital channels for voice or data and one 16 kbps channel for low speed data (up to 9,600 baud) and signalling. 2B+D is carried on one or two pairs of wires de- pending on the interface, the same wire pairs that today bring a single voice circuit into your home or office. See ISDN.

U-interface

A twisted pair subscriber loop that connects the NT1 reference point to the ISDN network, as defined in the I.411 Recommendation. This interface provides basic rate access with an operating frequency of 160 kbps and an information rate of 144 kbps. Under U.S. regulations, this also marks the line of demarcation between cus- tomer-owned equipment and the public network.

V.32

9.6 kbps, 2-wire duplex modem standard.

videoconferencing

The real-time, usually two-way, transmission of digitized video images between two or more locations. Videoconferencing requires a wideband transmission facil- ity. Transmitted images may be freeze-frame (where television screen is repainted every few seconds to every 20 seconds) or full motion. Bandwidth requirements for two-way video conferencing range from six MHz for analog, full-motion, full- color, commercial grade TV to 56 kbps for digitally-encoded freeze-frame to 1.544 kbps for high-quality, full-color, full-motion TV.

X.25

A packet data transfer protocol for the B and D-channels. Defines the interface be- tween data terminal equipment (DTE) and data circuit terminating equipment (DCE) for terminals operating in the packet mode and connected to public data networks by dedicated circuits.

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