[US] Selected Laws Governing the Disclosure of Customer Phone Records by Telecommunications Carriers / Congressional Research Service, 10 March 2008
PDF - http://www.fas.org/sgp/crs/misc/RL34409.pdf
"Telephone records contain a large amount of intimate personal information. Recent years have seen a rise in the use of this information for marketing and even for criminal purposes. The purchase and sale of telephone record information, therefore, became a booming business. Websites and data brokers claiming to be able to obtain the phone records for any phone number within a few days abounded."