Cisco CallManager Dial Plans
By using Cisco CallManager, you are able to allow for greater growth and functionality
within your network because it was designed to be integrated with
Cisco’s Internet Operating System (IOS) gateways.
Cisco CallManager dial plans are usually created to handle two types of calls,
internal and external:
Internal calls are those calls initiated and terminated on Cisco IP phones
that are included (registered) to the Cisco CallManager cluster.
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294 Chapter 9 • AVVID Dial Plans
External calls are those calls passed through a PSTN gateway or a Cisco
CallManager that originate across a WAN connection.
Figure 9.2 is a network designed to handle calls destined for the WAN and
the PSTN. For this setup, voice calls would set the preference for the WAN and
would only be routed to the PSTN if the WAN were down or unavailable.This
routing takes place transparently to the user. In Figure 9.2, the Cisco
CallManager Gatekeeper is a router assigned to manage this specific task as a
gatekeeper.This router could also handle other items, but often it is best to have
the router taking care of just Gatekeeper functions.