Data Stations - AT&T MERLIN LEGEND Data Manual

Data Communications with This System

Data Stations

A data station is a combination of equipment, such as a personal computer
(PC), printer, or fax machine, connected to the system with a modem or a data
module. The modem or data module sends information to and from the data
terminal and, in many cases, provides dialing and answering capability. The
data communications capability of the modem or data module is similar to that
of a telephone—it places, maintains, and ends a data call.
Two types of data stations can connect to the system—analog and digital.
Analog and digital data stations can include a telephone for users who need
simultaneous voice and data capability.
Analog Data Stations use modems to send and receive information. A
modem converts digital signals from the data terminal to analog signals.
The analog signals are then sent as continuous electrical waves in the voice
frequency band, The modem places, receives, or maintains the data call
over the regular telephone company network or with another data station
inside the system.
Digital Data Stations use a data module such as the Integrated Services
Digital Network (ISDN) 7500B Data Module to send and receive digital data.
A data module does not convert the digital signal to an analog signal. The
digital signal is sent as a sequence of separate electrical impulses. The data
module places, receives, or maintains the data call over digital telephone
company facilities such as ISDN Primary Rate Interface (ISDN-PRI) or with
another data station inside the system.
Calls between analog data stations and digital data stations are possible only if
the system includes a conversion resource to convert signals from analog to
digital or digital to analog. To do this conversion, modems are connected to
data modules to make a modem and data module pair.
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Data Stations