SWITCHING PLAN FOR TELEPHONE TOLL SERVICE 445 



Programming the Establishment of the General Toll 



Switching Plan 



The full application of the general toll switching plan involves a 

 large number of individual rearrangements of plant layout, the 

 establishment of certain new circuit groups and the rerouting of a 

 considerable amount of switched business, the conversion of the 

 switching offices to the terminal repeater arrangement, and the 

 modification of the transmission requirements of certain of the circuits. 

 The date at which these rearrangements will be completed is naturally 

 different for different sections of the country and is determined by 

 the regular program of plant additions and rearrangements to take 

 care of increasing business and of needed service improvement. The 

 existence of a comprehensive plan of this sort insures that the program 

 of rearrangements as carried out will be along the lines of greatest 

 economy and maximum improvement in service. The present plans 

 of the telephone companies in the United States and Canada indicate 

 that the plan as now established will be very closely approximated 

 by the actual plant in the course of about five years. 



Future View 



Such a plan as has just been discussed is naturally not a static 

 thing but is subject to continual modification to bring it into corre- 

 spondence with changed conditions. In connection with such changes 

 it is of interest to consider briefly the probable long time trend of the 

 development of the plan. 



One possible ultimate development would be the increasing con- 

 nection of primary outlets to a single regional center so that ultimately 

 only one regional center would be necessary. If this were to take 

 place, the regional center would undoubtedly be Chicago. Fig. 12 

 is interesting as showing the extent to which the primary outlets 

 already are connected directly with Chicago, over one half of them 

 having such direct connection. 



If Chicago ultimately became the only regional center, it would 

 reduce the maximum number of switches to three. It seems evident, 

 however, that such a plan would have many disadvantages. It seems 

 clear that with such an arrangement, numerous secondary regional 

 centers would be necessary to avoid uneconomical back-haul of large 

 amounts of traffic, and the economies of such an arrangement do not 

 look promising. Furthermore, it would lead to a tremendous con- 

 gestion of through switching at one point, this congestion going far 

 beyond the limits of economical concentration and leading to serious 

 operating difficulties. 



