A General Switching Plan for Telephone Toll Service 



By H. S. OSBORNE * 



This paper outlines a comprehensive plan for improved switching of long 

 haul toll telephone traffic in the United States and Eastern Canada. A brief 

 discussion is given of the methods of designing the toll plant to give ade- 

 quate transmission efficiency for all connections established in accordance 

 with this plan. This includes a new method of providing amplification at 

 intermediate switching points replacing the cord circuit repeatei method. 



ON January 25, 1915, telephone service was, with due ceremony, 

 inaugurated between the Atlantic and Pacific Coasts of this 

 country. This occasion marked a great step forward both technically 

 and commercially. Before that time, the limit of practicable telephone 

 transmission had been about 1,500 miles. The transcontinental 

 service was made possible by the completion of numerous important 

 developments and particularly by the perfection of telephone repeaters 

 and of means for applying them to long wire circuits. 



Until then the Pacific States and their neighboring states had been 

 isolated telephonically from the eastern and midwestern parts of the 

 country. The demonstration of commercially practicable telephone 

 circuits across the continent gave a great impetus to the idea of 

 universal service, that is the provision of a telephone plant such that 

 telephone service could be given at commercially attractive rates 

 between any two telephones in the country. 



In the fifteen years since the opening of the first transcontinental 

 circuits, the ideal of universal service has to a large extent been 

 realized. Practically all the telephones of the United States and a 

 large part of Canada now have provision for connection with the 

 countrywide toll telephone network, more than 99 per cent being 

 included. To achieve universal service, however, involves a great 

 deal more. Circuits must be provided in such numbers and so 

 arranged that connections between any two telephones can be estab- 

 lished quickly and without too many intermediate switching points. 

 Also the telephone plant must be designed for such standards of 

 transmission that these connections, when established, permit satis- 

 factory conversation. In general, the technical advances which have 

 been made during the last fifteen years to achieve the present standards 

 of toll service have been described from time to time before the 

 American Institute of Electrical Engineers, and it is not within the 

 scope of this paper to review them. 



* Presented at Convention A. I. E. E., Toronto, June 1930. 



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