TELEPHONE SYSTEM OF THE UNITED STATES 



37 



that the conversation is over. Her work is thus greatly simpUfied 

 and the operation of the board is extremely rapid. 



Fig. 28 — Manual straightforward tandem board for handling suburban toll calls. 

 Trunks from originating offices terminate on plugs at the rear of the keyboard. 

 Tandem completing trunks appear in jacks in the face of the switchboard. Incoming 

 calls indicated by flashing of lamp associated with trunk cord. 



Dial Tandem 



Dial tandem systems have been designed for handling suburban 

 toll trafific in areas where a large proportion of the central offices are 

 of the dial system and also to facilitate handling the complex sub- 

 urban traffic around the large metropolitan areas, such as New York, 

 Boston, Chicago and Philadelphia. The type of dial equipment, in 

 general, corresponds with the type used for the local traffic in the 

 same area. 



For use in connection with calls from dial offices, the dial tandem 

 usually requires no operators at the tandem office. The originating 

 operator in the dial office who handles the short haul traffic controls 

 the selection of the trunk to the terminating office. 



In some of the large metropolitan centers, dial tandem apparatus 

 of the panel type is employed also for handling calls from manual 



