3.5 Multisite Dial Plan Overview

This topic describes multisite dial plans.

Dial Plan Requirements Multisite Deployments with Centralized Call Processing Multisite Deployments with Distributed Call Processing
Access and site codes
  • Allows routing independent of directory numbers
  • Solves overlapping and nonconsecutive directory-number ranges
PSTN access
  • Gateways selected based on local route group
  • For TEHO, gateways selected per destination with local gateways as backup
  • Single gateway or set of gateways per cluster
  • For TEHO, intercluster trunk selected per destination with local gateways as backup
Gateway and IP phone backup
  • MGCP fallback for remote MGCP gateways
  • SRST for remote IP phones
  • CFUR for phones at other sites
Scalability ILS, GDPR, SAF, and CCD

In multisite environments with centralized call processing, you can use these dial plan solutions:

  • Access and site codes: By adding an access code and a site code to directory numbers of remote locations, you can provide call routing that is based on the site code instead of on directory numbers. As a result, directory numbers do not have to be globally unique, although they must be unique within a site.
  • Implementing PSTN access: You can implement PSTN access within a Cisco Unified Communications Manager cluster by using route patterns, route lists, and route groups. The applicable gateway or gateways are selected by the local route group feature. When implementing TEHO within a Cisco Unified Communications Manager cluster, you use the same dial plan configuration elements; however, you have to configure more route patterns (one per TEHO destination), which makes the configuration more complex. The primary route group refers to the TEHO gateway or gateways. The secondary route group is determined by the local route group feature.

    In a multisite Cisco Unified Communications Manager deployment with distributed call processing, each site has its own cluster. In such a deployment, you implement PSTN access by configuring a single gateway (or set of gateways) per cluster. When implementing TEHO in a multicluster deployment, you configure intercluster trunks between the clusters. Then you must add a route pattern per TEHO destination in each cluster. The route pattern refers to the corresponding TEHO trunk as the primary path and uses the local route group feature for the backup path.

  • Implementing gateway and IP phone backup: Survivability features for remote MGCP gateways and remote phones are provided by MGCP fallback and Cisco Unified Survivable Remote Site Telephony (Cisco Unified SRST) or Cisco Unified Communications Manager Express in SRST mode, and CFUR.
  • Scalability: In large distributed call-processing deployments, you can use GDPR, an application that uses the ILS, and CCD, an application that uses Cisco SAF, to simplify dial plan implementation.