When adding (or editing) a new personal contact in the TeleConsole, you will notice an option to toggle the status of a contact to be available for View (by) public.
Public in this case refer to all the users on the phone system in your company. Once this is enabled, the contact will not only appear in your own list of Personal contacts, but also appear in the the Personal contacts of every other user in the company. In other words public contacts are shared by everyone in your company, while non-public contacts are only available for you.