Data Communications - AT&T MERLIN LEGEND Release 3.1 System Planning Manual

Terminology
Data Communications Equipment (DCE). Data station equipment that
enables the transmission of data over digital or analog telephone lines
and trunks. DTE requires DCE as follows:
— Modem. A type of data communications equipment that converts the
DTE's outgoing digital signals into analog signals for transmission
over regular (analog) telephone company lines. Another modem at the
receiving data station converts the analog signals back into digital
signals for reception by the DTE (for example, a PC). An analog data
station uses a modem as its DCE.
— ISDN Terminal Adapter. A type of data communications equipment
that transmits digital signals over digital telephone company facilities,
for example, PRI. A digital data station uses an ISDN terminal adapter
(such as the ExpressRoute 1000 or 7500B data module) as its DCE.
Data Terminal. Data station equipment (for example, a PC, host
computer, LAN workstation, Group IV fax machine, or a group video
conferencing installation) from which data is input and/or output. A data
terminal uses data communications equipment (DCE) to transmit and
receive the digital signals it requires.
Modem/ISDN Terminal Adapter Pool. A special type of hardware
configuration that combines one or more pairs of DCEs to enable
communication between modem and ISDN terminal adapter data
stations. A pair consists of one modem and one ISDN terminal adapter.
Modem/ISDN terminal adapter pools are set up in one of two ways
depending on the type of data station being used to send data: analog-
to-digital or digital-to-analog. For more information about these pools, see
application note, MERLIN LEGEND Communications System Modem
Pooling .
Data Hunt Group (DHG). A data calling group typically used to distribute
calls to modem/ISDN terminal adapter pools that have more than one pair
of DCEs. For more information about DHGs, see the application note,
MERLIN LEGEND Communications System Modem Pooling .
Video System. Equipment that allows desktop or group video
conferencing. This equipment connects either directly or through an
ISDN terminal adapter to an MLX jack on the MERLIN LEGEND system. If
the MLX port is administered as a 2B Data port, the video systems can
use both of the B-channels assigned to the MLX port to provide full-
motion video. Many video applications also support data sharing and/or
transfer. In some configurations, an MLX telephone may be connected in
a passive bus arrangement.
NOTE:
If the video system is connected to the MLX jack through an ISDN
terminal adapter, unless the ISDN terminal adapter itself supports 2B
Data communications, it is recommended that the MLX port NOT be
administered as a 2B Data port.

Data Communications

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