Traffic Engineering Techniques for Determining Trunk Requirements in Alternate Routing Trunk Networks

M A R C H 1954 195!,, American Telephone and Telegraph Company Copyright, Traffic Engineering Techniques for Determining Trunk Requirements in Alternate Routing Trunk Networks By C. J. T R U I T T (Manuscript received November 23, 1953) In 1945 the Bell System embarked on an extensive study urith the purpose of developing a program for operator toll dialing on a nationwide basis. Operator toll dialing had been done, of course, on a limited scale in various parts of the country for many years, bid the concept of this program ivas one of nationwide proportions carried on urith a uniform numbering plan* arrangement and a completely integrated trunking system which woidd handle traffic at a high speed between any two points in the United States and Canada, even in the busier hours of the day. Implementation of this program required the development of new switching mechanisms and the exploitation of carrier transmission potentialities to a degree never before achieved. Great strides had already been made in these fields, resulting in the practical development of the coaxial cable system and the first toll crossbar switching office installed at Philadelphia in 1943. But the very core of the nationwide dialing plan was the proposal to revolutionize the method of traffic distribution so as to combine high speed handling over the intertoll trunk network with a highly efficient use of facilities. The method of accomplishing is called "engineered alternate routing" * W. H. N u n n , Nationwide Numbering Plan, Communication and Electronics, 2, Sept., 1952 and B.