Telephone directory

In telephony, a telephone directory is a listing of telephone subscribers in a geographical area or subscribers to services provided by the organisation that publishes the directory. Subscriber names are generally listed in alphabetical order, together with their postal or street address and telephone number. It can be published in hard copy or in electronic form.

In the U.S., courts have ruled (in Feist v. Rural) that telephone companies do not have a copyright on telephone listings, which has meant availability of innovative telephone directory services on CD-ROM and the World Wide Web.

A telephone directory may also provide instructions about how to use the telephone service in the local area, may give important numbers for emergency services, utilities, hospitals, doctors, and organisations who can provide support in times of personal crisis. It may also have civil defence or emergency management information as well as advertising.

A telephone directory may also be called a phone book or may be known by the colour of the paper it is printed on.

White pages generally indicates personal or alphabetic listings.
Yellow pages generally indicates a business directory classified by business type or services provided, often with paid advertising.
Other colours may have other meanings: For example blue is used for government listings in some countries, green is sometimes used for government agencies.

A reverse directory, or criss-cross directory, is a telephone directory in which the entries are in in order by address (first by city, then by street, then by house number), and were used to find out the name of a subscriber with a particular address or to find the neighbors of a particular address. They were fairly common until the 1960s as a separately published book, or sometimes included at the back of the regular telephone directory with each section on a different colour paper. Printed reverse directories have become less common with the availability of telephone databases on CD-ROM and on the Internet with advanced searching features.

They are not well known to the general public since they have generally been available on a limited basis to telephone companies or government officials, although genealogists and private investigators know which public libraries have them in their collection. In addition, some telephone companies have made the information generally available through little known services, such as the "2080 service" in Chicago (now discontinued), where a call to the exchange and the number 2080 produced an operator who would give the name and address of any other number in that exchange.

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