SWITCHING PLAN FOR TELEPHONE TOLL SERVICE 



431 



The part of the business on which it is most difficult to give a high 

 grade of service is naturally the scattering business between widely 

 separated points. In these cases each item of traffic, that is the 

 business between two specific points, is relatively small but the number 

 of items of traffic is great. The number of messages involved in 

 each item of traffic does not justify direct circuits and in very large 



LI 



15 



10 



1915 



1920 



1925 



1930 

 (EST.) 



Fig. 2 — Growtli in number of toll circuits — Toronto to Detroit. 



numbers of cases it is necessary, in order to provide a connection, 

 to make more than one intermediate switch. This applies at present 

 to six per cent of the long distance telephone business of the country. 

 All measures of the quality of service — speed, accuracy and trans- 

 mission — show that the difficulty of satisfactorily handling the service 

 increases rapidly with the number of intermediate switches involved. 

 The development of the toll business has led to a great increase in 

 the amount of business between large numbers of widely separated 

 points. There has also been an extensive trend toward concentration 

 of the plant used in handling the business in important toll offices 

 and along important routes. The long haul toll business is now 

 handled at about 2,500 "toll centers" out of approximately 6,400 



