AT&T MERLIN LEGEND System Reference Manual page 39

System Overview
1-12 Capabilities
1. Analog Voice and Analog Data Station includes a data terminal, a modem,
and an analog multiline telephone. A GPA is required to supply the tip/ring
(T/R) interface for the modem.
To provide the Simultaneous Voice and Data feature. two adjacent station
jacks on a 408, 408 GS/LS, or 008 module must be assigned.
2. On- or Off-Premises Analog Data-Only Station Includes a data terminal
and a modem. Connection to the control unit is through an off-premises
telephone jack on a 008 OPT module.
Analog Data-Only Station includes a data terminal and a modem.
3.
Connection is through a jack on a 012 (basic telephone) module on the
control unit.
4. Digital Voice and Analog Data Station includes a data terminal, a modem,
and an MLX telephone. An MFM installed in the telephone is required to
supply the T/R interface to the modem.
5. Digital Voice and Digital Data Station includes a data terminal, an lSDN
7500B Data Module, and an MLX telephone. The lSDN 75006 Data Module
supplies the RS-232 interface to the data terminal. The data station connects
through a jack on a 008 MLX module.
6. Digital Data-Station includes a data terminal and an ISDN 7500B Data
Module. When the 7500B is installed without an MLX telephone, a 440A4
terminating resistor is required. One station jack on a 008 MLX module is
assigned to connect this configuration.
Modem Pools and Data Hunt Groups
A modem pool (also called a conversion resource) is made up of one or more
pairings of an ISDN 7500B Data Module and a modem. Modem pools provide
resources that convert digital data signals to analog, or analog data signals to
digital, and allow users with different types of data stations to communicate with
each other.
A data hunt group (DHG) is a group of data stations of the same type (all analog
modems or all digital ISDN 7500B Data Modules) or is a group of one or more
modem pool pairings. A common extension number is assigned to each group
—for example, extension 771 can be assigned to the data module DHG used to
communicate with the local host computer, extension 773 can be assigned to
the modem DHG used to communicate with the local host computer, extension
774 can be assigned to the data module DHG used to communicate with the
workstation on a LAN, and extension 775 can be assigned to the modem DHG
used to communicate with the workstation on a LAN.
DHGs allow sharing of data communication resources by connecting users in a
round-robin fashion to the first available data station or modem pool pairing in
the group. Specific lines/trunks can also be assigned to ring directly into the
DHG so that outside callers can dial a published telephone number to reach the
DHG.
Figure 1-3 shows how modem pools assigned to DHGs can be configured to
allow analog and digital stations to communicate with each other.