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Glossary
BRI (Basic Rate Interface) A defined ISDN interface that includes two B channels and one D channel. Also known as 2B+D. B channels are used for voice and data while the D channel is generally used only for signalling within the telephone network.
Broadcast LAN transmission method used in bus topology networks that sends messages to all stations even though the messages are addressed to specific stations.
BTU See basic transmission unit.
CALC (Customer Access Line Charge) A Federal tariff charge, also referred to as an End User Common Line Charge (EUCL), or Subscriber Line Charge (SLC). Every ISDN line is charged one CALC or EUCL.
Call bumping The ability to receive an incoming call during a bonded outbound call.
CCITT (International Telephone and Telegraph Consultative
Committee) See ITU (International Telecommunication Union).
CD (Carrier Detect)
Centrex Local Public Exchange incorporating PBX facilities.
Channel 1) A path along which signals can be sent, for example data channel, output channel. 2) In data communication, a means of
Channel aggregation Channel aggregation combines multiple physical channels into one logical channel of greater bandwidth. With BRI ISDN connections, channel aggregation would combine the two 64 Kbps B channels into a single, logical 128 Kbps channel.
Clock Timing signal used in synchronous transmission.
CO (Central Office) The site where the local Telco switches reside for the telephone system's call routing and all other functions. This is the Telco side of the local loop. If the distance between your location and the central office switch exceeds 18,000 feet and/or the signal loss exceeds 35.0 dB, a repeater must be installed to allow ISDN service.
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