A1 VoIP Requirements
58 Getting Started
Are layer 2 or higher switches used?
Use of repeater hubs can increase the network load, and therefore may result in degradation
in speech quality.
To ensure the performance, it is strongly recommended that you use layer 2 or higher switches.
Are category 5 (CAT 5) cables used?
When connecting network devices, make sure to use CAT 5 cables. If other types of cables are
used, communications may not be carried out normally.
A1.4 QoS (Quality of Service)
Some routers permit the configuration of priority control features. This allows the router to give
higher priority to voice packets and lower the rate of loss and delays during transmissions,
hence improving speech quality. It is strongly recommended that you use this feature,
especially in networks where traffic is heavy.
Typically, a router identifies what packets to pass in priority by checking the value in the ToS
field of the header of IP packets. The VoIP Gateway Card has the ability to set the ToS field of
outgoing voice packets (see "2.2.3 Voice Communication Parameters" in the VoIP Gateway
Card Programming Guide). When the card is appropriately configured, the router can give
voice packets from the card higher priority.
Consult your network administrator when setting the ToS field, as the setting value must
conform to the router’s specifications.
Note
Some switches also permit the configuration of priority control features. For more
information, consult your network administrator.
*2 For the actual setting values, refer to "2.2.1 Network Parameters" in the VoIP Gateway
Card Programming Guide.
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