The phone number used to access a Cisco Unity server. For example, subscribers dial a pilot number when logging on to Cisco Unity. The phone system that Cisco Unity is integrated with dials a pilot number when transferring callers to a greeting. Other voice messaging systems dial a pilot number when sending messages to Cisco Unity via AMIS.
An extension number that is the single number that is called to access a particular service, such as paging or ephone-hunt. The number is for an ephone-dn that is not associated with any phone. Calls to the pilot number are redirected to actual ephone-dns according to configuration instructions.