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Changing the Termination Straps on the ISDN S/T
Interface
The ISDN S/T link interface module has two configurable straps that control whether the
ISDN LINE is set to terminated or unterminated.
Jumper straps W5 and W6 are factory installed to configure the module as TERMINATED.
The TERMINATED position is used when the bridge/router is the only ISDN device
connected to the ISDN circuit.
Removing the W5 and W6 straps sets the module to UNTERMINATED. This allows this
bridge/router to be part of a daisy-chain connection to the ISDN circuit by using the ISDN
AUX connector.
Figure C-5 ISDN S/T Module Termination setting jumpers
Connecting to the ISDN-U Link Module
The connection to the central office is made with the RJ45 connector on the panel
of the U Module. Pins 4 and 5 are used for the connection. These pins are polarity
insensitive.
The Ferrite module included with the ISDN U Module must be installed on the cable that is
connected to the ISDN U Module. The Ferrite module must be installed approximately two
inches from the RJ45 connector at the bridge/router end of the cable. The cable must pass
through the Ferrite module twice with a Single loop around the Ferrite module.
Figure C-6 Ferrite Module Installed on the Cable.