FUNDAMENTAL PLANS FOR TOLL TELEPHONE PLANT 



83: 



ill turn one segment of tlie Chicago "region" which serves a somewhat 

 larger area than shown by Fig. 5. 



Under this arrangement, toll calls between two tributaries in the Hib- 

 l)iiig toll center area can be completed by switching at the toll center. 

 In a similar manner, any two points within the Duluth tandem outlet 

 area can be served by switching at Duluth. The same treatment also 

 applies for connections between any two points in the same sectional 

 center area or in the same regional center area. For example, a connection 

 from Hibbing to any i)oint within the Chicago region (which involves 

 more than six states as shown in Fig. 7) requires no more intertoll links 

 than nibbing to Duluth, Duluth to Minneapolis and Minneapolis to 

 Chicago, and a corresponding number of links on through to another 

 sectional center, and primary or tandem outlet to the toll center desti- 

 nation. Circuits between the toll center and tributaries are not referred 



HIGH USAGE 



GROUPS 



DES MOINES :SC) 



CAGO (RC) 



DAVENPORT (PO) 



Fig. 5 — Intertoll trunks between Davenport, Iowa and Hibbing, Minnesota, 

 showing alternate routing possibilities. 



