Until recently, if you are looking for a person’s contact information, you have to consult a standard telephone directory. And there was no guarantee that you would find the contact information in the directory.
With a reverse phone lookup, the tables turn. Originally, law enforcement such as the Federal Bureau of Investigation and state police used this service to trace the origins of distress and prank calls. Today, the same service is available to the public, and anyone can perform a reverse phone lookup to put a face to a number. To do this, the service pools publicly available information from public directories and private telecommunication databases and make them available on a searchable database. The only required search parameter is the phone number. Upon query, the database will return the associated user details registered with a telecom service.