In olden days the system of directory is to find a number just by furnishing the details of the number holder. For example if you need a contact number of your professor then you may need to search the accordingly by using his name and other contact information such as residential address. But this system is no more required I think as your professor may be connected to you with the help of face book or twitter or any other similar social media. Use completely free reverse phone lookup with name as this is a cost effective and efficient way to know the details by a phone number in your hand. Without an account in social media it is even hard to speak with our wives now a day and so the system needs a change.
Why do you need a reverse look up?
The change that is even appreciated by all of the phone users is the system of using the directory to find out information about the number that you know. It is a direct reverse of the traditional old system and try the completely free reverse phone lookup with name that provides you with the contact information such as residential town and address if you give the number that the one have whom you need to track down. This directory is available in two forms both publically accessible and privately accessible.
Many government organizations such as law enforcement use this system in order to retrieve the details about someone who is needed to be contacted or need to be in surveillance. But also individuals could these systems through private databases that is well updated by the owning authorities or individuals who are interested in doing so. But the directory that you are referring plays the games most often.