a logic low state which indicates that the system is idle fig6 is a flow chart that illustrates the steps executed by the software program in the keyboard and display unit for the interconnect embodiment shown in fig3 the first step shown in this figure is to place the five bits representing a telephone number or instructions into the shift register 47 for temporary storage the second step is to activate switch line 52 indicating that a number is ready to be transmitted the software program then waits for a period of time sufficient to allow transceiver 12 to switch to the receive data mode at this point switching network 36 causes handset 11 to be switched out by bidirectional bus transceiver 44 and simultaneously causes the data stored in the shift register to be released onto the data lines and transmitted to the transceiver 12 this is followed by a wait period to insure that the transceiver has received the data the switch is then inactivated to place the handset back on line in a typical installation the transceiver and the interconnect module are stored in the trunk of a car the handset is located adjacent the driver 39 s seat and the keyboard and display unit placed atop the dashboard adjacent the windshield where it is easily accessible by the driver when the driver or a passenger wishes to place a telephone call he or she.