This feature can only be used by calling from a device that is registered to the same domain as the auto-attendant.
In order to use this feature, you must know the access code to reach the desired greeting. Each greeting will have a different access code. To find the access code of a greeting, first Manage the menu prompt from the relevant auto-attendant configuration page as shown in the image below.
This will open a modal window showing details of the Menu Prompt. The access code is shown in the field labelled ‘Star Code to Record’.