882 THE BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER 1952 



numbering plan covering the entire country with a minimum number of 

 digits to give each customer a distinctive number. It also obviates the 

 need for extra expense to make step-by-step toll offices satisfactory 

 operating elements of the plan in those locations where CSP features are 

 not essential. 



The automatic and almost instantaneous selection of alternate routes 

 makes it possible to give ^'irtual no-delay service without greatly in- 

 creasing the cost of outside plant and to make multi-switch connections 

 at a speed comparable to that for local service. 



The translating equipment simplifies administration of the plan which 

 demands coordination of activities on a nationwide basis. 



The numbering plan, the switching plan and the CSP equipment which 

 implements them make it feasible to offer nationwide dialing service 

 to customers without the aid of operators when automatic charging 

 facilities and local office switching arrangements for handling the three 

 extra digits of the national nimiber are provided. It will be readily ap- 

 preciated that so far as the CSP switching equipment is concerned it is 

 immaterial whether the digits it receives come from an operator or from 

 a customer. The call will be routed to its destination and .supervision 

 for charging purposes will be furnishes in the same manner in either 

 event. 



The new system represents an important step in the process of con- 

 tinually improving the long distance switching methods of the Bell 

 System with consequent improvement of the service to all telephone 

 customers in the United States and Canada. 



REFERENCES 



1. J. J. Pilliod, "Fundamental Plans for Toll Telephone Plant," pp. 832 of this 



issue. 



2. L. G. Abraham, A. J. Busch and F. F. Shipley, "Crossbar Toll Switching 



System," A.I.E.E. Transactions, 63, June Section, pp. 302-309, 1944. 



3. C. A. Dahlbom, A. W. Horton, Jr. and D. L. Moody, "Application of Multi- 



frequency Pulsing in Switching," A.I.E.E. Transactions, 68, June Section, 

 pp. 505-510, June 1949. 



4. W. H. Nunn, "Nationwide Numbering Plan," pp. 851 of this issue. 



5. F. J. Scudder and J. N. Reynolds, "Crossbar Dial Telephone Switching Sys- 



tem," A.I.E.E. Transactions, 58, May Section, pp. 179-192, 1939. 



6. N. A. Newell and A. Weaver, "Single Frequency Signaling for Telephone 



Trunks," Presented at Winter General Meeting of A.I.E.E., Jan. 31, 1951. 



7. F. A. Korn and J. G. Ferguson, "The Number 5 Crossbar Dial Telephone 



Switching System," A.I.E.E. Tranasctions, 69, First Section, pp. 233-254, 

 1950. 



8. J. Meszar, "Fundamentals of the Automatic Telephone Message Accounting 



System," Presented at the Winter General Meeting of A.I.E.E., Jan. 31, 

 1951. 



