Far south networks Com.X, Руководство администратора

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Com.X Administrator Guide
Page 91
Field Content
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QSIG: protocol for switching between PBXs
Signaling role When configured as Terminal, the device is an ISDN TE,
connected to the telco NT. When configured as Network, this
port acts as though it is an ISDN NT device. This is useful when
the Comma device is placed between the PBX and the telco NT,
e.g. for least-cost routing.
Overlap dialing Enabling this setting will result in digits being transmitted across
the PRI link as they are dialed, as opposed to the full number
being collected before dialing. Overlap dialing allows a
destination number to be specified partially resulting in the first
stage of a routing path being established before the remaining
digits arrive.
Table 9: PRI port configuration
3.6.5 Removing devices
To remove a device configuration, select Remove from the device's context menu.
Note: Any of the device's ports that are included in trunk groups will be removed
from the groups, outbound routes that make use of the ports will no longer be
associated with the ports and any extensions associated with device ports or
channels will become unassigned.
3.6.6 Echo cancellation
When two phones, B and C are in a call, and the person's speech at phone C is
reproduced at phone B, some of the audio exiting B's earpiece re-enters B's
microphone and is returned as echo. Analog lines exacerbate this problem due to
additional reflection of audio in the electronic circuitry. The result of audio feedback at
B is that person C hears his/her own voice after a short delay i.e. echo occurs.
The person hearing the echo should look to the remote party for the cause of the
echo and not to their own phone and system. If both parties experience echo, both
systems should be investigated.
In analog phones, both the 2-wire to 4-wire converter (hybrid) and the handset can
introduce echo. The Com.X impedance parameters are aligned with South African
telecommunications standards. Non-compliant handsets with a large impedance
mismatch are likely to introduce noticeable echo. The delay introduced by VoIP
based systems can result in the returned echo becoming noticeable to the person
who is speaking.
The degree of echo and the delay between the original audio and the echo is a
function of the handset, gain settings, potential wiring problems and the audio
transmission path.
The Com.X products incorporate a sophisticated Echo Canceller for each telephony
channel (BRI, PRI or analog). The algorithm adapts to the detected audio feedback
within a configurable timeframe of 16, 32 or 64 milliseconds, and attempts to create
an identical image of the echo, which is then removed from the audio signal prior to
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