3Com NBX 100, Installation Manual

Page: 21 / 306

Overview of NBX 100 Hardware Components 21
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VOL - MOH This mini-jack (mono or stereo) accepts Music-On-Hold
audio from the line-output of a CD player, tape player, or the like. The
adjusting screw next to the jack controls the MOH volume.
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PAGING This RJ11 connector provides an audio output or a dry
contact switch connection for use with a public address system.
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EXT ALERT This RJ11 connector is reserved for future use.
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BNC 10B2 and 10BT UPLINK MDI-X These connectors provide
alternative means for connecting to an Ethernet hub.
These are two media points for a single port. They cannot be used
simultaneously.
If you use the Uplink connector, be sure to program the switch or router
on the other end for 10BASE-T half-duplex operation.
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COM1/COM2 The COM1 connector provides a DTE (Data Terminal
Exchange) connection for use with a VT100-compatible control
terminal. COM2 is reserved for future use.
See “Testing the Installed Hardware” in Chapter 3 for information about
what the LEDs indicate during system startup and operation.
4-Port Line Card The NBX 100 4-Port Line card connects up to four local analog telephone
lines to the NBX 100. The system can support up to 25 line cards (100 CO
telephone lines) using multiple chassis. See “Installing LAN Connections”
later in this chapter for information on how to daisy-chain chassis using
the NBX 100 Hub card.
Figure 3 NBX 100 4-Port Line Card
Each 4-Port Line card contains the following LEDs and connectors:
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LEDs (labeled 1 through 4) These show the status of each line.
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PFT (Power Fail Transfer) Connector If a card loses power, its line
connection for Port 1 switches to the PFT connector. You can then
attach an analog telephone to maintain an outside connection (useful
for emergency access). For international users, see “Power Fail
Transfer” on page 37 for information on a feature limitation.