for each operating area were designed to give maximum economy 

 considering both present and future conditions. This naturally re- 

 sulted in many cases in the selection of the larger cities of a given 

 operating area although in some cases other points were chosen as 

 primary outlets due to their advantageous location, for example, at 

 the point of intersection of a number of important toll routes. The 

 routings provided by the Plan are supplemented by direct routes or 

 other routings where the volume of traffic or other conditions made 

 this desirable. These other routings, however, are designed to provide 

 service conditions at least as good as those provided by the General 

 Toll Switching Plan. 



Figure 23 shows the application of the General Toll Switching Plan 

 to the country as a whole. In order to tie together with a minimum 

 number of switches the interconnected groups of primary outlets, each 

 one of these primary outlets has direct connection to at least one very 

 important switching point designated as a " regional center," and each 

 regional center has direct connection to every other regional center in 

 the country. This means that any two primary outlets in the country 

 are connected together with a maximum of two intermediate switches. 

 The numbers of switches between telephone points of different classi- 

 fications are shown by Fig. 24. It will be noted that in the limiting 



Fig. 24 — Numbers of switches between telephone points of different classifications. 



case of toll centers in different regional areas and not connected directly 

 to any regional center, the maximum number of intermediate switches 

 is four. 



The present location of regional centers and primary outlets in the 

 General Toll Switching Plan is shown in Fig. 25. There are, as will 



61 



