NYT: Phone Companies See Their Future in Flat-Rate Plans

The trend toward flat-rate, unlimited local + long distance calling has spread from mobile networks to nearly all the major US wireline service providers. With usage and distance-based pricing models out of favor, carrier will rely on service bundling to sustain the revenue. Commentators tell The New York Times that network usage typically has doubled when all-you-can-eat plans are introduced.
http://www.nytimes.com/2003/05/23/business/23PHON.html