3Com 3C10402B Administrator's Manual page 175

compression affects audio quality and bandwidth, see
Settings" on page
Audio Source Gain — Enables you to adjust the audio gain to resolve
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volume issues.
CAUTION: Do not change your Audio Source Gain settings unless you
are instructed to do so by a technical support representative.
To modify span audio controls:
1 Click the appropriate link:
PSTN Gateway Configuration > IT1 Spans
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PSTN Gateway Configuration > ISDN PRI Spans
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PSTN Gateway Configuration > ISDN BRI Spans
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2 Click the MAC address of the span you want to modify.
The number of channels supported per span depends on the
configuration of the Digital Line Card. E1 cards support 30 channels per
span.
3 Click the Audio Controls tab and see the online Help for more
information.
4 Enable the Echo Canceller Enabled check box if you want to turn on echo
cancellation.
There are two situations in which it might be desirable to disable echo
cancellation on a T1 Digital Line Card:
If a system is connected to a telephone carrier (Central Office) by a T1
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Digital Line Card, and the telephone carrier guarantees to provide
echo cancellation on all channels at all times.
If T1 Digital Line Cards directly connect two systems, and the network
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between the two is completely composed of digital circuitry, thus
eliminating sources of echo.
You can enable or disable echo cancellation for each T1 Digital Line Card.
However, you cannot enable or disable echo cancellation on individual
channels.
CAUTION: Before you enable echo cancellation for a T1 Digital Line Card,
verify that the card is configured for DS1 operation and not ISDN PRI
operation.
5 Click OK.
Configuring and Managing Digital Line Cards
37.
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"Audio