# Voice Clustering Programming Overview

To configure a cluster you must complete the following tasks:

- Plan the cluster.

- Enable the optional features at each cluster element.

- Upgrade cluster element software (required for clusters of greater than 250 elements).

- Add Elements to Network Elements form.

- Define the Cluster.

- Add Elements to the Cluster.

- Use System Data Synchronization to synchronize the following data across the cluster elements:

- system form data

- user and device data (between a pair of resilient controllers)

- Program ARS routes between the cluster elements.

- Program the IP trunks and XNET trunks.

- Configure the telephone directories.

- Review the Remote Directory Numbers forms.

- Program changes to the network for route optimization, if required.