Automatic Testing of Transmission 



and Operational Functions of 



Intertoll Trunks 



By H. H. FELDER, A. J. PASCARELLA and 

 H. F. SHOFFSTALL 



(Manuscript received October 19, 1955) 



Conditions brought about by nationwide dialing increase intertoll trunk 

 maintenance problems substantiaUy. Under this switching plan with full 

 automatic alternate routing there is a considerable increase in the amount 

 of multiswitched business, and as many as eight intertoll trunks in tandem 

 are permissible. In addition, operator checks of transmission on the connec- 

 tions are lost on most calls. These factors iynpose more severe limitations on 

 transmission loss variations in the individual trunks and throw on the 

 maintenance forces additional burdens of detecting defects in the distance 

 dialing network. 



New methods of analyzing transmission performance to locate the points 

 where maintenance effort will be most effective continue to be studied. The 

 automatic testing arrangements described in this paper enable the main- 

 tenance forces to collect over-all transmission loss data quickly and with a 

 minimum of effort. They also facilitate the collection of such data on groups 

 of trunks in a form to make statistical analyses easier. The use of these 

 testing arrangements will permit the maintenance forces to keep a closer 

 watch on intertoll trunk performance and will assist in disclosing trouble 

 patterns. 



INTRODUCTION 



The advent of nationwide dialing, especiall}' with full automatic 

 alternate routing, has presented additional problems in the maintenance 

 of intertoll trunks. Transmission reciuirements are more rigorous, the 

 intertoll trunk connections are more complex, and certain irregularities 

 in the performance of the distance dialing network are difficult to detect. 

 Automatic test equipment has been provided to aid and increase the 

 efficiency of over-all testing. This equipment is capable of automatically 



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