Reverse phone books provide a service which is just the opposite of the services provided by a traditional phone book.  In a phone book, you search by a person or a business name and you are provided the address and phone number related to the name you began with.  In the case of reverse phone books, you start with a phone number, landline or cell, and use this number to locate the associated name and address of the person or business as well as other relevant details.

You can make use of reverse phone book services for free or pay a fee to subscribe to them. 
Generally, when you use a free reverse phone book service, the results you get might be disappointing or very minimal.  So, a paid service is a better bet.

In paid services, you can either take a single number search service or a short term, annual or life membership.

Various information companies are making available reverse cell phone lookups that are attained from utility resources.  These services are available online.

Some community services that are web based also offer a reverse telephone directory of known fund raisers, telemarketers and companies that contact consumers over telephone. By performing a search of the telephone number which showed up on as the caller ID, it becomes possible to gain relevant information about the calling company before forming an association.

Besides the Internet, printed reverse phone directories have been made by the telephone companies for many-a-years and made available to the phone companies, law enforcement agencies and public libraries.
 
With the advent of the 1990s, businesses found an opportunity in providing fee based reverse telephone lookups and by the early 2000s advertising-based reverse online directories became available.

Online reverse phone books are available in abundance  on the World Wide Web and searching with keywords such as reverse phone number lookup, reverse phone book, number lookup, reverse lookup and locate by phone number  will throw up relevant links.

As far as the physical reverse phone books are concerned, in the United States, is possible for landline phone subscribers to have their name removed from the book on payment of a fee. However, this type of delisting is not possible for cellular numbers.  The reason being, each cellular carrier has a separate database.
         
There are some nations where the reverse phone book service, whether online or in a physical form is just not available for the public.  In such places, a simple search engine search by the phone number could throw up relevant information if the information is present in any page on the World Wide Web.