Nortel HomeOffice II, User Manual

Page: 27 / 214

Line Card Configuration Guide 9
June 1999 Description
Circuit pack
The HLC conforms to the Common Features Specification for IPE line cards.
LED
The LED indicates card enabled/disabled status. The LED indicates a successful
Self-Test by blinking three times each time you start or reset the card. If, after
passing its self-test, the card’s LED remains lit, check the switch to see if the
card is enabled. If the card is enabled and the LED remains lit, this indicates a
problem at the switch.
Echo canceling
The Digital Signal Processor (DSP) provides echo canceling to all 16 channels
of HLCs equipped with firmware load HLC 1.15 and later. Echo canceling
isolates and filters unwanted signals, or echoes, from the main transmitted
signal.
Echo is often experienced in long-delay communication when a person’s speech
echoes in the receiver. A tail, in echo canceling terms, is the portion of your
speech that returns to you in an echo. You usually measure tail length in
milliseconds. (1000 ms = 1 second). See “SET ECHO (S E)” on page 120.
Note: The particular routing of each call through the public switched telephone
network (PSTN) can effect the need for echo canceling.
Multiple-agent (user) access
Each HLC has 16 channels (numbered 0–15). Each channel has access to only
one ISDN connection. Multiple-agent functionality allows the you to assign up
to eight different users (agents) to a single HLC channel. However, only one of
these users (agents) can have access to the channel at any one time.