3Com NBX 100, Руководство администратора

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Dial Plan Tables 39
Least Cost Routing
Dial Plan Table
The Least Cost Routing table (table ID 3) defines how to route calls in
order to minimize the cost of those calls.
Example: You might use two different long distance carriers, one for a
specific geographic region, and one for all other areas of the country. In
the Least Cost Routing table, you can create entries that route calls
differently for those two geographic areas. Each country uses a different
method to accomplish this. In the United States, you can specify the area
codes that apply to a geographic region. In France, you can specify a
carrier by adding prefix digits to the telephone number.
By default, internal telephones specify the Least Cost Routing table as
their least cost table. Typically, devices associated with the Incoming dial
plan table (Line Card ports, Digital Line Card ports, and H.323 gateways)
do not use the Least Cost Routing table.
The Least Cost Routing table is optional. If it does not exist, the system
uses the Internal table routing destinations. If you have entries in both the
Least Cost and Internal tables for the same purpose, the behavior of the
dial plan can be confusing. Therefore, 3Com recommends that you
accomplish least cost routing using Internal Table entries. See
TimedRoute
Create , TimedRouteEntry Create , and TimedRouteOperation Create .
Example: If a new entry in the Internal table appears not to work, it is
possible that the system is using an entry from the Least Cost table
instead. To avoid such conflicts, accomplish least cost routing using only
the Internal table. 3Com strongly recommends that you keep the dial
plan as simple as possible by using only the Internal table.
Adding New
Dial Plan Tables
If you are sharing the system with another company or group and want
to control calls differently at the two sites, you can add a fourth table.
Example: You assign one extension range to Company A and a different
range to Company B. The fourth table controls the extension range for
Company B, so that outbound calls from Company B’s extensions use
only their external telephone lines.
You might also need a fourth table if a single company had two sites but
only one NBX system. In order to properly route emergency (911) calls,
you use the fourth table to define which extensions use each dedicated
911 telephone line.