CROSSBAR DIAL TELEPHONE SWITCHING SYSTEM 



93 



FROM 20 LINES 



^ 



1 2 3 4 5 6 7 & 9 10 II 12 13 14 15 16 17 le 19 



\, 



■*■ 9 

 -»• 8 

 -^ 7 

 -»■ 6 

 -»• 5 



TO TEN 

 TRUNKS 



Fig. 8 — Simple trunking arrangement with a single 200-point crossbar switch. 



in Fig. 8. By adding other switches in this manner, any number of 

 lines may be given access to the ten horizontal trunks. 



To obtain greater trunking access, two groups of switches known as 

 "primary" and "secondary" are used. Figure 9 illustrates this 

 primary and secondary switch arrangement as used in the "line link" 

 switch frames and in various forms throughout the crossbar office. 



SUBSCRIBER 

 LINES 



t t 



DISTRIBUTING 

 FRAME 



FRAME HAS 

 ACCESS TO 

 100 DIST JUNCTORS 

 100 LINE JUNCTORS 



PRIMARY SECONDARY 



Fig. 9 — Primary-secondary trunking arrangement. 



