Data Communications Networking Devices - 4th Ed.pdf

12 _______________________________ FUNDAMENTAL WIDE AREA NETWORKING CONCEPTSFigure 1.7 Foreign exchange FX) service. A foreign exchange line permits many terminaldevices to use the facility on a scheduled or on a contention basisthan the cost of direct distance dialing. An FX line can be viewed as a mixed analogswitched and leased line. To use an FX line,a user dials a local number which isanswered if the FX line is not in use. From the FX,the information is transmittedvia a dedicated voice line to a permanent connection in the switching of®ce of acommunications carrier near the facility with which communication is desired. Aline from the local switching of®ce which terminates at the user's home of®ce isincluded in the basic FX service. This is illustrated in Figure 1.7.Figure 1.8 Terminal-to-computer connections via analog mediums. A mixture ofdedicated, dialup, leased and foreign exchange lines can be exployed to connect localand remote terminals to a central computer facility