3Com NBX, Руководство по установке

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for voice over the WAN, verify that the WAN offers adequate
bandwidth, and that the gateways can be configured to provide the
correct routing information.
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External paging amplifier. The NBX system includes an RJ-11 jack to
connect an externally powered paging amplifier.
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Standard telephone for power-fail situations. In the United States, you
can connect a standard POTS (Plain Old Telephone Service —
2500-series compatible) telephone to an RJ-11 connector on the front
of an NBX Analog Line Card or a V3000 Analog.
What Effect Does an
NBX System Have on
a LAN?
A 10 Mbps Ethernet LAN can support a fully configured, fully utilized
NBX 100 system. A 100 Mbps Ethernet LAN can support a fully
configured, fully utilized V5000, V3000, or V3001R system. That is, a 10
Mbps Ethernet LAN with 200 “voice devices” (3Com telephones and
outside telephone lines) can support the toll-quality audio provided by
the NBX 100 system even when all 200 devices are in use. Similarly, a
100 Mpbs LAN can support toll-quality audio with a fully configured
V5000, V3000, or V3001R system. If you use an Ethernet switch, verify
that it supports the 802.1P and 802.1Q specifications.
Silence Suppression and Bandwidth
Silence suppression enables you to reduce network traffic. When silence
suppression is enabled, the NBX device detects silence in the audio
stream, such as a pause in conversation, and stops sending packets. The
receiving NBX device generates white noise for the periods represented
by silence indicator packets so that the listener does not hear true silence
and worry that the call has been disconnected. The receiving NBX device
can be another 3Com telephone, or for external calls, it can be an analog
line port or a channel on an NBX Digital Line Card.
A careful listener might notice the difference between generated and
actual background noise, so silence suppression is turned off by default.
Silence Suppression settings result in a small compromise to audio quality.
Do not enable Silence Suppression unless you are trying to solve
bandwidth constraint issues.
You can enable or disable silence suppression for the entire system or for
individual telephones and line card ports.