Unity ships with a bulk import tool - it's not downloadable off the site since it's tied to back end code that cannot be updated without upgrading Unity - all the tools on the CiscoUnityTools.com site are independant and can be installed/upgraded without affecting the running Unity system.
You'll find the bulk import tool in the Tools Depot or in the Unity program group under the start menu. It's called "Cisco Unity Bulk Import". It links to an app in \commserver\utilities\CiscoUnityBulkImport\ if the link is missing for some reason.