For non-subscribers, you need to purchase the appropriate amount of licenses for guest directory user access. The SKU is:
Speech Connect Guest User for Cisco Unity Connection (for names in the company directory that do not have a Cisco Unity Connection user license) | UNITYCN-SCGUEST |
I believe the use of contacts ties into this as well. When you create system contacts in Cisco Unity Connection Administration and enable them to be listed in the directory, they can then be accessed by users from the Connection directory. This allows callers to transfer to the extension of the system contact. I would try that first to see if it allows you to add a contact and enable them for directory access.
Hailey