Understanding Partitions and Calling Search Spaces

Understanding Partitions and Calling Search Spaces

A partition comprises a logical grouping of directory numbers (DNs) and route patterns with similar reachability characteristics. Devices that are typically placed in partitions include DNs and route patterns. These entities associate with DNs that users dial. For simplicity, partition names usually reflect their characteristics, such as "NYLongDistancePT," "NY911PT," and so on.

A calling search space comprises an ordered list of partitions that users can look at before users are allowed to place a call. Calling search spaces determine the partitions that calling devices, including IP phones, softphones, and gateways, can search when attempting to complete a call.

When a calling search space is assigned to a device, the list of partitions in the calling search space comprises only the partitions that the device is allowed to reach. All other DNs that are in partitions that are not in the device calling search space receive a busy signal.

Partitions and calling search spaces address three specific problems:

Routing by geographical location
Routing by tenant
Routing by class of user

Partitions and calling search spaces provide a way to segregate the global dialable address space. The global dialable address space comprises the complete set of dialing patterns to which Cisco Unified Communications Manager can respond.

Partitions do not significantly impact the performance of digit analysis, but every partition that is specified in a calling device search space does require that an additional analysis pass through the analysis data structures. The digit analysis process looks through every partition in a calling search space for the best match. The order of the partitions that are listed in the calling search space serves only to break ties when equally good matches occur in two different partitions. If no partition is specified for a pattern, the pattern goes in the null partition to resolve dialed digits. Digit analysis always looks through the null partition last.

You can associate partitions with a time schedule and a time zone. Associating a partition to a time schedule and a time zone allows configuration of time-of-day routing for calls that are coming into a partition and the associated calling search spaces of the partition. See "Time-of-Day Routing" for more information.

If you configure a calling search space both on an IP phone line and on the device (IP phone) itself, Cisco Unified Communications Manager concatenates the two calling search spaces and places the line calling search space in front of the device calling search space. If the same route pattern appears in two partitions, one contained in the line calling search space and one contained in the device calling search space, Cisco Unified Communications Manager selects the route pattern that is listed first in the concatenated list of partitions (in this case, the route pattern that is associated with the line calling search space).

Note : Cisco recommends avoiding the configuration of equally matching patterns in partitions that are part of the same calling search space or part of different calling search spaces that are configured on the same phone. This practice avoids the difficulties that are related to predicting dial plan routing when the calling search space partition order is used as a tie breaker.

Before you configure any partitions or calling search spaces, all directory numbers (DN) reside in a special partition named <None>, and all devices are assigned a calling search space also named <None>. When you create custom partitions and calling search spaces, any calling search space that you create also contains the <None> partition, while the <None> calling search space contains only the <None> partition.

Note : Any device that is making a call can explicitly reach any dial plan entry that is left in the <None> partition. To avoid unexpected results, Cisco recommends that you do not leave dial plan entries in the <None> partition.

See the "Local Route Groups" chapter in the Cisco Unified Communications Manager Features and Services Guide for an explanation of local route groups and the details of provisioning route groups, device pools, route lists, partitions, route patterns, and calling search spaces in a local route group scenario.