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

About Data and Video Communications

Modem Data Stations

A modem data station uses a modem as its DCE to send and receive data.
The modem converts digital signals from the DTE at the originating station into
analog signals so the data can be transmitted over analog telephone
lines/trunks. At the receiving station, the modem converts the analog signals
back to digital signals so the DTE at that end can accept them. A modem may
provide dialing and answering capabilities for a modem data station; if not, a
telephone can be connected to dial out.
NOTE:
If an analog multiline telephone is connected to the modem data station, the
telephone and data station can be used at the same time. A voice call can be
made or received while a data call is in progress. A data call cannot be made or
received while a voice call is in progress.
A modem data station can be used to make analog data calls either over the
telephone company network or to a data station inside the system.
The interface for a modem data station is the tip/ring (T/R) interface provided by
one of the following:
A General-Purpose Adapter (GPA), connected to an analog multiline
telephone
A port on a T/R module (012, 016, or 008 OPT)
A Multi-Function Module (MFM) adjunct on an MLX telephone
There are different types of modem data stations, depending on the data station
capabilities:
Modem voice and analog data (analog voice-and-data)
Modem data only
Modem data and MLX voice
Each of these use different equipment as described in this section.
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Data Communications