THE BELL SYSTEM 



TECHNICAL JOURNAL 



VOLUME XXXII SEPTEMBER 1953 number 5 



Copyright, 1963, American Telephone and Telegraph Company 



Transmission Design of Intertoll 

 Telephone Trunks 



By H. R. HUNTLEY 



(Manuscript received June 12, 1953) 



At the 1952 Minneapolis summer meeting of the A.I.E.E. a symposium* 

 on the nationwide toll switching plan went into such features as the funda- 

 mental plant layout, numbering plan, toll switching and automatic account- 

 ing equipments. The present paper is intended to round out this coverage of 

 the plan with a further discussion of the transmission features. 



THE PROBLEM 



In the new nationwide toll switching plan using switching machines 

 the layouts of toll circuits and the routings of traffic will be quite different 

 from that of the earlier plans which were based on manual switching. 

 Individual calls can be switched so fast and cheaply that switching is no 

 longer a limiting factor and circuits can be laid out and used in such a way 

 as to obtain maximum economy with few, if any, limitations from the 

 switching standpoint. 



An example of these changes is given in Fig. 1 which shows in (a) 

 the circuit groups which would be used to handle a given (assumed) 

 flow of traffic on a manual basis and in (b) the groups which would be 

 used to handle the same traffic on a dial basis. In (a) there are 44 different 



* Trans. A.I.E.E., 71, Part I, Sept., 1952. 



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