Data Communications Networking Devices - 4th Ed.pdf

1.3 TYPES OF SERVICES AND TRANSMISSION DEVICES ______________________________ 11Figure 1.6AT&T WATS service area one for an access line located in Georgiathe United States,illustrating the composition of the service areas for each state.Similarly,a time-of-day rate schedule for each state based upon state service areasis also published by AT&T.In general,since WATS is a service based upon volume usage its cost per hour isless than the cost associated with the use of the PSTN for long-distance calls.Thus,one common application for the use of WATS facilities is to install one ormore inward WATS access lines at a data processing center. Then,terminal andpersonal computer users distributed over a wide geographical area can use theinward WATS facilities to access the computers at the data processing center.Since International 800 service enables employees and customers of UScompanies to call them toll-free from foreign locations,this service may experiencea considerable amount of data communications usage. This usage can be expectedto include applications requiring access to such databases as hotel and travelreservation information as well as order entry and catalog sales data updating.Persons traveling overseas with portable personal computers as well as of®cepersonnel using terminals and personal computers in foreign countries who desireaccess to computational facilities and information utilities located in the UnitedStates represent common International 800 service users. Due to the businessadvantages of WATS its concept has been implemented in several foreigncountries,with inward WATS in the United Kingdom marketed under the termFreefone.FXForeign exchange FX) service may provide a method of transmission from agroup of terminal devices remotely located from a central computer facility at less