AT&T MERLIN LEGEND Installation & Maintenance Manual page 178

Installation
Hardware Requirements
A modem pool requires an ISDN 7500B Data Module(PEC2164-
BDM) and a 2224G modem or its equivalent. Since the 7500B in
a modem pool operates without an MLX telephone, a 100-ohm
440A4 terminating resistor adapter (PEC 2709-A59) must be
installed on the line near the 7500B.
The ISDN 7500B Data Module can be configured as a stand-
alone by ordering a WP-90110-L1 power unit (PEC 21625). The
7500B can also be configured in a multiple-mount arrangement
by ordering a Z77A data mounting (PEC 21626), which provides
a common power supply for up to eight data modules. Both the
power unit and the data mounting require a 115-VAC power
outlet. Neither is provided with the data module, and both must
be ordered separately.
The modem used in a modem pool must have the following
features:
full-duplex operation
10-bit code support (start, 8 data bits, stop)
RS-232 asynchronous interface
any or all of the following data rates: 300, 1200, 2400, 4800,
and 9600 bps
supports DTMF dialing via the RS-232 interface
ability to turn on or maintain the Clear-to-Send indicator when
it is ready to receive ASCII dialing sequences from the data
module in response to a Data-Terminal-Ready signal from the
data module
ability to keep the Data-Set-Ready lead on (and not turn it off)
during transition from the interactive dialing mode to the data
mode
ability to terminate a data call or dialing sequence when the
data module turns off its Data-Terminal-Ready lead
3-70 Data Adapters