Some Basic Concepts of Translators and Identifiers 

 Used in Telephone Switching Systems 



By H. H. SCHNECKLOTH 



{Manuscript Received April 26, 1951) 



The functions and typical designs of translators as applied to automatic tele- 

 phone switching systems are first reviewed. The fundamental similarity of some 

 existing translation schemes is noted and a discussion given of the factors which 

 can be juggled to obtain economic application of such schemes. 



Identifiers and their uses are next described and some processes of identifica- 

 tion are shown to have much in common with those of translation. Complications 

 encountered in commercial application are discussed. Some needed improve- 

 ments in general designs, possibly by new approaches, are indicated. 



Finally, the author points out the frequent occurrence of translation and 

 identification processes in switching elements which are not labeled "translators" 

 or "identifiers" and suggests that future improvements in translation and identifi- 

 cation methods may consequently be useful in switching circuit networks in gen- 

 eral. 



Introduction 



Those concerned with the technical details of automatic telephone switch" 

 ing circuits usually regard a switching system as made up of a number of 

 types of blocks or elements named in accordance with their main accom- 

 plishment in the train of events in handhng a telephone call. 



Each of these elements is important as a useful cog in making the system 

 work. Some of them, however, have an added distinction, if not a glamour, 

 because their introduction to the switching world made possible funda- 

 mental changes in switching technique or in the service which could be 

 ofifered to subscribers. 



Two such elements are translators and identifiers. They will not be de- 

 fined or explained until later, but a few words concerning their importance 

 may be in order here. 



These elements were not used at all in early types of automatic switching 

 systems. The invention of the translator in 1905, by Mr. E. C. Molina,^ 

 and the philosophy that accompanied it are now generally credited with 

 having laid the groundwork for the Bell System's adoption of systems of the 

 common control type. In these, the paths necessary to reach a called number 

 are not selected by the calling dial but by equipment which is common to 

 many switching elements. The dial merely furnishes the customer's orders 

 to the common equipment which, through the translation process, can set 

 up a more suitable series of paths than is possible within the Umitations of 

 direct dial control. 



» "Historic Firsts": Translation, p. 445 of Nov. 1948 Bell Laboratories Record. 



588 



