TELEPHONE SYSTEM OF THE UNITED STATES 



39 



offices. With this arrangement operators are, of course, required at 

 the tandem board. The tandem operator receives a request from 

 the originating operator for the office and number called and by means 

 of keys establishes the connection by dial switching apparatus to the 

 called subscriber in case he is in a dial office or transmits the required 

 information to the terminating office operator in the case of a manual 

 office. Figure 29 shows an installation of panel tandem operators' 

 equipment and ¥\g. 30 shows one section of this equipment in greater 

 detail. 



Fig. 31 — ^Step-by-step dial tandem board. Calls completed to the terminating 

 dial subscriber station by means of the 10 button key set shown on the keyboard. 

 Incoming calls automatically distributed to an idle operator. 



A modified form of step-by-step tandem equipment using operators 

 has been installed in step-by-step areas for handling calls from manual 

 offices to dial offices in cases in which it was not advisable to equip 

 all the subscriber operators' positions with dials. This equipment 

 includes, in addition to the selectors, a simplified type of switchboard 

 as shown in Fig. 31. 



Long Distance Service 

 General 



For the longer hauls the subscriber is connected to a toll board 

 operator who completes and supervises the toll message. This method 

 is called the toll board method of operation, and is used for most all 



