Chapter 30 Modem installation 175
Multiservice Switch 7400 Hardware Installation, Maintenance, and Upgrade 6.1S2
Modem installation supporting information
Modem selection
You do not need to configure any Nortel Networks Multiservice Switch
software in order to connect a modem to the CP. However, you must be able
to configure the modem and assemble the cable in accordance with the
information contained in the following sections:
• “Setting modem DIP switches” (page 522)
• “Modem cable specifications” (page 175)
• “Configuring the modem software” (page 217)
The modem used as an example hookup is a 56K modem manufactured by US
Robotics, which includes their older Sportster series modems. Choose a
modem that supports the same dip switch settings and AT software
commands. The modem must also support the dumb mode so that the
Multiservice Switch device will not reconfigure the modem while it is on-
hook.
Modem cable specifications
You cannot use the DCE V.24 cable assembly with product engineering code
NTBP25 to connect a modem to the device’s CP port 1. The connector on the
faceplate requires a customized DB-9 cable.
You need the following components in order to assemble the cable:
• a V.24 serial interface cable
• a male 25-pin D-sub connector to connect to the modem
• a male 9-pin D-sub connector to connect to port 1 on the faceplate of the
CP in the device
If your device is in a cabinet, determine the length of cable required by
measuring the distance from the faceplate of either CP through the cable
management guide to the rear of the shelf. You can install the modem inside
the cabinet and, optionally, fasten it to the cable management guides.
The cable and its connectors must be custom-made according to the table
“Pinout for the DB 9-pin connecting to the modem DB 25-pin” (page 176).
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