# Managing the Telephone Directory in a Cluster

Directory numbers in the network or cluster are managed with the help of the Remote Directory Number (RDN) Synchronization feature.

Any telephone directory entries that you add, modify, or delete at an element are automatically distributed as shared data updates to the other elements in the network via System Data Synchronization (SDS).

Related Topics

- About Networks

- About Clusters

- How Calls are Routed in a Cluster