In most ISDN (Integrated Services Digital Network) installations, an NT-1 must be connected to the ISDN line to power the ISDN line from the Network Interface box to the ISDN device. Check with your telephone provider to see if one is needed.
The NT-1 also has lights indicating the state of the ISDN line. Typically, an NT-1 will have Power, U Loop Back, and S/T&U lights.
Also because an ISDN line needs power and would be unusable in the event of a power outage, a user might want to consider connecting the NT-1 to an UPS (Uninterruptable Power Supply).
Below is a diagram showing how to connect an NT-1. An NT-1 may have multiple S/T ports, it does not make a difference which port you use.
Network Interface Box
---------WALL---------------------|-------------------------WALL---------
AC Power |<---Wall jack, RJ-11 or RJ-45)
| |
| |
-------------- |<---Use cable that ships with the NT-1
| |
POWER |
----------------------- |
| | |
| Plug into U loop-> |------
| |
| * NT-1 * |
| |
| Plug into S/T loop->|------
| | |
----------------------- |
|
|<---Use RJ-45 that ships with the
| H.320 Card
|
H.320 Card installed in computer
Plug into the RJ-45 jack
Pin Assignments
===============
+=========================================+
| S/T Connector Pin Assignments |
+=====+==============+=====+==============+
| Pin | Function | Pin | Function |
+=====+==============+=====+==============+
| 1 | ------------ | 2 | ------------ |
+-----+--------------+-----+--------------+
| 3 | RX+ | 4 | TX+ |
+-----+--------------+-----+--------------+
| 5 | RX- | 6 | TX- |
+-----+--------------+-----+--------------+
| 7 | -40 VDC | 8 | GND |
+=====+==============+=====+==============+
+=========================================+
| U-Line Connector Pin Assignments |
+=====+==============+=====+==============+
| Pin | Function | Pin | Function |
+=====+==============+=====+==============+
| 1 | ------------ | 2 | ------------ |
+-----+--------------+-----+--------------+
| 3 | ------------ | 4 | Tip |
+-----+--------------+-----+--------------+
| 5 | Ring | 6 | ------------ |
+-----+--------------+-----+--------------+
| 7 | ------------ | 8 | ------------ |
+=====+==============+=====+==============+
+=========================================+
| Power Connector Pin Assignments |
+=====+==============+=====+==============+
| Pin | Function | Pin | Function |
+=====+==============+=====+==============+
| 1 | +7.5 VDC | 2 | -40 VDC |
+-----+--------------+-----+--------------+
| 3 | GND for +7.5 | 4 | GND for -40 |
+=====+==============+=====+==============+
DIP Switch Settings on Alpha Telecom UT620 NT-1 Device
======================================================
+============================================================+
| DIP Switch Assignments |
+========+=================+=================+===============+
| Switch | Function | ON | OFF |
+========+=================+=================+===============+
| 1, 2 | S/T-Termination | Yes | No |
+--------+-----------------+-----------------+---------------+
| 3 | Bus Timing Mode | Short Passive | Point-to- |
| | | bus | point, or |
| | | | extended |
| | | | passive bus |
+--------+-----------------+-----------------+---------------+
| 4 | PS2 Selection | SP62020 | AD62010 AC/DC |
| | | switching power | power adapter |
| | | supply | |
+========+=================+=================+===============+