Polycom 3725-77601-001H manual How Least-Cost Routing Works, Example of Least-Cost Routing

Dial Plan Setup Operations

You cannot use least-cost routing when:

•The route cannot be identified.

•The required resources are unavailable.

•Bandwidth limitations exist on the WAN.

How Least-Cost Routing Works

Each LCR table defines dial strings, which include the country code, area code, prefix, and a weighted cost for commonly made calls. You usually create one LCR table per site.

The following table is an example of an LCR table.

Country Code	Area Code	Prefix	Weighted Cost
1	408	565	0
1	408		0
1	650		0
1	415		5

The CMA system compares the dial string for a call to the dial strings in LCR tables. The dial string can match at the country code, area code, or prefix level. The CMA system reads the “# of digits to strip” field to determine how many digits to remove.

Note

For areas of the United States that do not require you dial an access code before the area code, exclude this number when you define the number of digits to strip.

Before determining the final call routing, the CMA system considers cost (through LCR tables), bandwidth resources (through site topology and device group policies), and gateway availability.

Example of Least-Cost Routing

Company ABC has three sites: Site A in San Jose, CA, Site B in Monterey, CA, and Site C in Washington, D.C. All sites have gateways.

LCR Tables for Three Sites

The LCR tables included area codes that are used frequently in each site and considered that calls are made frequently from Site C to Southern California.

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