MACHINE SWITCHING TELEPHONE SYSTEM 



R3 



operator, upon assigning a trunk, presses the assignment key of that 

 crunk, which temporarily attaehes her keyboard to a sender and 

 simultaneously to the incoming trunk which she has assigned. As 

 shown in Fig. 24, the incoming trunk terminates on an incoming 

 selector which has access to final selectors on which the called num- 

 ber appears, in the same manner as described before. 



The operator now sets up on her numbered keys the number de- 

 sired, and this information is transmitted immediately to the sender. 

 These keys, which lock mechanically, are released after a fraction of 

 a second by a magnet controlled by the sender and aie ready for the 



Fig. 



"B" Positions in Machine Switching Office 



next call. The "B" operator's sender now controls the incoming 

 and final selectors in the same manner as the subscribers' senders, 

 causing the incoming selector to choose an idle trunk to a final selector 

 having access to the desired group of 500 numbers. The final selector 

 reaches its destination in the manner previously described and, as 

 soon as the line is found, the sender is released. 



Fig. 25 shows a line of cordless positions. The section at the 

 left is the cable turning section, having nothing to do with the oper- 

 ation of the board. 



