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Chapter 7 Dial Plan

Dial Plan Guidelines for Multi-Site IP WAN Deployments with Centralized Call Processing

This approach has the significant advantage that only a single, un-restricted calling search space is
required for each location (that is, one per branch). Because the dialing privileges are implemented
through the use of blocked route patterns (which are not locally significant), the same set of blocking
calling search spaces can be used in all branches.

For a system with N branches and, for example, 5 different classes of service, N+5 calling search spaces
are required. This number is in contrast with the 5

N calling search spaces required by the typical

approach.

Special Considerations for Extension Mobility

When using the Extension Mobility feature, the dialing restrictions of a phone are a function of the
logged-in (or logged-out) status of the phone. Typically, a logged-out phone should be restricted to
calling other phones and services (such as 911), but access to local or toll calls through the PSTN are
restricted. Conversely, a phone where a user is logged-in should allow calls according to that user's
dialing privileges and should route those calls to the appropriate gateway (for example, a co-located
branch gateway for local calls).

Use the following general approach to configure calling restrictions when using Extension Mobility:

Create an unrestricted calling search space for each location and assign it to the phone's device
calling search space. This calling search space should contain partitions featuring route patterns that
route the calls to the appropriate gateway for the phone's location (for example, a co-located branch
gateway for emergency services and a centralized gateway for long distance calls).

Create a calling search space with partitions featuring blocked route patterns and assign it to the
lines in the Default Logout Device Profile. The blocked route patterns should block all calls except
those to be allowed when no user is logged in (for example, emergency services and internal
extensions).

Create user device profiles with line calling search spaces containing partitions featuring blocked
route patterns for those types of calls that are not part of the user's dialing privileges. For instance,
if a user has access to all types of calls except international, that user device profile should be
configured with a calling search space featuring a blocked route pattern for 9.011!

Automated Alternate Routing

The automated alternate routing (AAR) feature enables Cisco CallManager to establish an alternate path
for the voice media when the preferred path between two intra-cluster endpoints runs out of available
bandwidth, as determined by the locations mechanism for call admission control (CAC).

The AAR feature applies primarily to centralized call processing deployments. For instance, if a phone
in branch A calls a phone in branch B and the available bandwidth for the WAN link between the
branches is insufficient (as computed by the locations mechanism), AAR can reroute the call through the
PSTN. The audio path of the call would be IP-based from the calling phone to its local (branch A) PSTN
gateway, TDM-based from that gateway through the PSTN to the branch B gateway, and IP-based from
the branch B gateway to the destination IP phone.

AAR can be transparent to the users. You can configure AAR so that users dial only the on-net (for
example, 4-digit) directory number of the called phone and no additional user input is required to reach
the destination through the alternate network (such as the PSTN).

Note

AAR does not support CTI route points as the origin or the destination of calls. Also, AAR does not
support the Extension Mobility feature.