Abstracts of Technical Articles by Bell System Authors (01 April 1944)

Applied Physics, January 1944. Jour. S. M. P. E., January 1944. 203 204 BELL SYSTEM TECHNICAL JOURNAL three units, the switching equipment itself which is wholly mechanical, together with the so-called # 4 and # 5 switchboards. The # 4 board is a cordless, key-typed call distributing board which is used in conjunction with the new switching system for such calls as must be given to an operator by offices not equipped for intertoll dialing. 

The operators at this board function as combined inward, through and tandem operators, thus eliminating the provision of separate units to provide these particular services. In brief, there is no basic difference between the essential operation of the # 5 board and the conventional through board where delayed traffic is handled; however, operators handling calls at this board must make use of the new switching system to obtain both the calling and called offices by dialing. 

Prior to the cutover the first trainees were given experience by handling some 300,000 test calls of every conceivable traffic characteristic. These were routed through the new system to break in the equipment and to shake down potential troubles. Two weeks prior to cutover a dress rehearsal was held, at which time about ten per cent of the circuits were put through their paces. To provide information of value for future installations, arrangements were made for liberal provision of registers and meters to measure any and all phases of the various steps performed by the equipment.