Reverse phone book directory Spend some time to do research. Try to find out if the unknown number that you have is a landline number or a cell number. That way, you can narrow down your options as to how to proceed with your investigation. Landline numbers can be easily looked up using yellow pages or any online directories. If you think it is a cell phone number, you might have to spend more time online because information for cell numbers are not readily available to the public. This is the time when you have to look for a real reverse phone number service. Legitimate cell reverse look up providers charge a small amount for every search that you do. This amount covers the cost they spend on updating their database regularly. Reverse Phone Book Directory will give you instant access to: * Owner Information * Address History * Carrier Details * Location Details