Telos Zephyr Xstream User Manual page 57

ISDN Interface
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IMPORTANT!
As with any piece of modern electronic gear, it is advisable that precautions be taken to
prevent damage caused by power surges. Standard telephone line surge protectors can be used
to offer some degree of protection at the U interface. Special protectors are available for the S
interface.
It is the user's responsibility to ensure that adequate protection is provided.
Section 4 has additional information.
U Interface (2 wire) ‐ for use in the USA and Canada
The ISDN U interface is for connection with "raw" 2B1Q BRI ISDN circuits as provided primarily in
the USA & Canada. When this jack is connected you will be using Zephyr Xstream's built‐in NT1
(Network Terminator). This is a 6‐position/4‐pin miniature modular jack with the following pin
out.
PIN
1 No Connection
2 No Connection
3 Line (R)
4 Line (T)
5 No Connection
6 No Connection (Top)
ISDN U interface connector. Note, the polarity of
the line connections should not matter.
U Interface Sync LED
A green LED, located below the U interface jack, shows the status of the built‐in NT1. Normal
status is indicated by the LED being lit. Rapid flashing (about five times per second) indicates a
loss of the ISDN at the lowest (physical) level. If the NT1 can contact the central office (or an
active U repeater), the LED will blink slowly (about once per second) as the S connection
between the NT1 and the rest of the ISDN interface occurs. The LED will come on solidly when
all handshaking is completed and the basic line connection is good. If this LED does not light
continuously, once you have connected your ISDN circuit, you may wish to skip ahead to Section
13 (Deep Tech Information ‐ Troubleshooting) for information on troubleshooting the problem.
USER'S MANUAL
FUNCTION
Section 3: GUIDED TOUR of the HARDWARE 45
U
U Sync LED