Caller applications enhance the TUI with custom menus and prompts that guide callers to the appropriate recipient. A caller application contains all custom menus and prompts associated with a unique mailbox.
When you create a caller application, you associate the caller application with a site. The storage server for that site deploys the caller application to each application server in the cluster. You can use the Microsoft Management Console (MMC) to import and export caller applications as XML data to other storage servers in a multisite environment.
Because Messaging stores each caller application as an LDAP Contact in a central mailbox, the system backs up caller applications each time you back up the message store.