108 THE BELL SYSTEM TECHNICAL JOURNAL, JANUARY 1956 



calls from custoniers in panel and No. 1 crossbar offices may be routed 

 through crossbar tandem cr other equivalent offices to telephones 

 anywhere in the country. 



CONCLUSION 



The new features developed for crossbar tandem will adapt it to 

 switching all types of traffic at many important switching centers of 

 the nationwide toll network. Of the 225 important toll switching centers 

 now contemplated, it is expected that about 80 of these will be ecjuipped 

 with crossbar tandem. 



REFERENCES 



1. Collis, R. E., Crossbar Tandem System, A.I.E.E. Trans., 69, pp. 997-1004, 1950. 



2. King, G. v.. Centralized Automatic Message Accounting, B.S.T.J., 33, pp. 



1331-1342, 1952. 



3. Nunn, W. H., Nationwide Numbering Plan, B.S.T.J., 31, pp. 851-859, 1952. 



4. Pilliod, J. J., Fundamental Plans for Toll Telephone Plant, B. S.T.J. , 31, pp. 



832-850, 1952. 



5. Shipley, F. F., Automatic Toll Switching Systems, B.S.T.J., 31, pp. 860-882, 



1952. 



6. Truitt, C. J., Traffic Engineering Techniques for Determining Trunk Require- 



ments in Alternate Routing Trunk Networks, B.S.T.J., 33, pp. 277-302, 1954. 



7. Clos, C, Automatic Alternate Routing of Telephone Traffic, Bell Laboratories 



Record, 32, pp. 51-57, Feb. 1954. 



