The Card Translator for Nationwide Dialing

The "Card Translator" was developed for the 4A toll crossbar system used at Control Switching Points (CSP) in the nationwide dialing network of offices. Although the many problems and conditions presented in the development and implementation of a nationwide dialing plan have been discussed in papers* by A. B. Clark, J. J. Pilliod, H. S. Osborne, W. H. Nunn, F. F. Shipley and others, it is necessary to restate some of these because of their effect on the translation problem and the features the card translator had to have in order to meet the nationwide dialing requirements. Translation is the process of converting the called destination code into information that is needed for the proper routing of the call. * B.S.T.J., 31, pp. 823-882, Sept., 1952. 1037 1038 THE BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER, 1953 NUMBERING PLAN For nationwide dialing it is necessary that each customer have a distinctive universal number. This numbering system is accomplished by dividing the country and Canada into about ninety numbering areas. Each of these areas is assigned a distinctive three digit code which, in order not to conflict with local office three digit codes, has either the digit "1" or "0" as the second digit. Within these numbering areas each local office will have a distinctive non-conflicting, name and number code. Since each customer in an office has a distinctive number, a corresponding distinctive nationwide universal number is thus provided. To reach a customer outside the local numbering area will require the dialing of three digits for the area code, three digits for the office code and four or five digits for the line number.