AT&T Merlin II Feature Module 2 Data Communications Manual page 26

Modem Pools
Modem pools are groups of modems and associated equipment used to
convert digital data signals to analog data signals or vice versa. Signals must
be converted in this way for:
• Outside calls to and from digital stations
• Internal calls between digital and analog endpoints
Putting modems in pools makes it easier for users to share a limited number
of modems. Each modem pool is used exclusively for either incoming or
outgoing calls.
Each modem configuration in a modem pool consists of:
A Modular Trunk Data Module (MTDM) with an RS-232-C Interface.
A 2212C or other compatible modem.
Where required, a Basic Telephone and Modem Interface (BTMI). BTMIs
are required if the modem connects to a jack on an analog module rather
than to a jack on a basic telephone module or to a dedicated outside line.
Modem Pools Using MERLIN II System Lines
Typically, modem pools handle calls that are placed and received through the
MERLIN II system control unit. The lines used for these calls maybe
assigned only to members of a modem pool or they may be shared with other
stations in the MERLIN II system. As Figure 2-3 shows, these configuration
require one station jack on a digital station module and one station jack on
either an analog station module or a basic telephone module.
FIGURE 2-3 Modem pool
Basic
telephone
module
Digital
station
module
Reserving Jacks for Computer Access and Modem Pools 2-15
for calls through the MERLIN II system control unit.
I