Circuit switched networks, such as cellular communications systems, generally offer only one class of service which is used primarily for voice calls. In a cellular communications system, voice calls compete with data calls for the same limited number of channels available in a particular cell or access point to the network. Service providers therefore cannot justify pricing data calls differently than voice calls, and as a result, cellular communications systems have not been extensively utilized as data networks.
Some service providers have sought to overcome the problem of single class service by deploying separate facilities to handle data calls on a reduced rate basis. Separate data facilities in a cellular communications system still can only reduce the cost of data calls to the extent that the capital investment for such facilities is lower than the cellular communications systems used for voice calls. Consequently, in existing cellular communications systems, the demand for voice call service sets the price that a carrier will rationally charge for competing data call service.