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8 | Section 2
Ordering Help
Appendix 3 to this manual describes the ISDN ordering process for USA/Canada in detail, and
Appendix 4 does the same for ETS-300 Euro-ISDN. Both include ready-to-go forms that can
be sent directly to your telephone company.
2.5 Connecting the Nx12 to ISDN
e Nx12 uses plug-in modules to attach to ISDN. ese ISDN modules have three modular
jacks. e type of jack will be either a 6 position RJ-11 style or an 8 position RJ-45 style
depending upon whether it is the version for USA & Canada or the rest of the world.
e correspondence between the interface slot to the system line number for is from left to right
when viewing the Nx12 from the rear. erefore, the leftmost jack in slot A would be lines one
and two, and the rightmost jack of an ISDN card in slot B would be lines 11 & 12
All ISDN BRI circuits must use the same ISDN protocol setting.
ISDN in USA & Canada: Using the U Interface
Connect the ISDN line from the telephone central office directly to the RJ-11 style U-interface
modular jack on the rear panel. Each module has 3 jacks and each jack has an associated LED.
IMPORTANT
Remember that the U interface connects to a long telephone line and can convey lightning
surges into the Nx12. Surge protectors intended for analog lines work to protect U-interfac-
es. We recommend that you install one for each line.
U-interface Status LEDs
e small green LED on the ISDN interface card near each U jack indicate the status of the
corresponding ISDN circuit. Rapid flashing (about five times per second) indicates a loss of
the ISDN at the lowest (physical) level. If the Nx12 can contact the central office or an active
U repeater, the LED will blink slowly – about once per second. e LED will come on solid
when handshaking is completed and all is OK. If these LEDs do not light continuously once
you have connected your ISDN circuits, you may wish to skip ahead to Section 6.4 for help with
troubleshooting the problem.
Nx12 U-interface (RJ-11)
PIN DESCRIPTION
1 N/C
2 N/C
3 Line R
4 Line T
5 N/C
6 N/C
Note that the polarity of the line connections doesn’t matter.