AT&T 7100 series See network channel-terminating equipment, See data communications equipment

GLOSSARY GL-7

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CSU

customer provided (premises) equipment (CPE)

customer service unit (CSU)

D4 framing format

D-channel

data-carrier detect (DCD)

data channel

data-circuit terminating equipment (DCE)

Data-Communications Access (DCA)

data communications equipment (DCE)

The terms channel service unit and customer service unit are both abbreviated to CSU and are both synonymous with network channel- terminating equipment. See network channel-terminating equipment.

Customer owned equipment that is not provided as part of the system but is to be connected to it.

See network channel-terminating equipment.

A format containing 12 frames. See also extended frame and frame.

The 16-kbps or 64-kbps packet-switched channel on an Integrated Services Digital Network basic rate interface (ISDN-BRI) or 64-kbps on an Integrated Services Digital Network primary rate interface (ISDN-PRI) packet-switched channel that carries signaling messages and packet- switched user data. A D-channel is the (IDSN-PRI) Q.931 signaling channel. (A D-channel can also carry data, but this capability is not used on a DEFINITY® Communications System Generic 2.) See also B- channel, and Q.930 and Q.931.

A data communications equipment (DCE) signal that shows whether the received data-channel line signal is within appropriate limits as defined by the DCE. See also data circuit-terminating equipment.

The means of transmission for and the intervening equipment used in the transfer of information in a given direction.

See data communications equipment.

On a System 85 and Generic 2, a feature that uses a unique analog data port to provide access to on-premises host computers for data endpoints with an analog interface (modem). These endpoints include analog telephones and attendant consoles. On a System 75 and Generic 1, the equivalent functionality is provided by using the same analog-line port circuit used to interface with analog telephones.

The equipment — usually a modem, data module, or packet assembler/disassembler — used for terminating the circuit that provides the connection between terminal endpoints. The circuit itself is not considered part of the DCE. Also called data circuit-terminating. See also data-carrier detect.