tie them together, the arrangement of the ticket distributing apparatus, 

 all have important effects upon the service rendered by and the 

 efficiency of the operating method. Changes in method, therefore, 

 frequently call for rearrangement of equipment. 



Trunking Methods Distinguished from Operating Methods 



As soon as the telephone business developed to the point where it 

 became necessary to connect together two telephones not served by 

 the same central office, the arrangements for interconnection between 

 the two offices became an important consideration. Offices are con- 

 nected together by trunks or toll lines and there must be arrangements 

 for operators to get into communication with each other promptly. In 

 general this is accomplished by signals transmitted over the circuit 

 which later is used for conversation, but sometimes a separate circuit, 

 known as a call-circuit, is used. The manner in which trunks are 

 arranged and used is known as trunking method, as distinguished 

 from operating method which has to do with the manner in which calls 

 are handled. Much of the trunking methods experience gained in 

 handling local traffic has been applied to the handling of toll calls. 

 The more important trunking methods are call-circuits, straight- 

 forward, ringdown and dialing. Any of these trunking methods may 

 be used with the various toll operating methods. 



Description of Trunking Methods 



Call-Circuit Trunking Method 



Under this method a call-circuit was provided between the two 

 offices. The terminating end was connected to an operator's receiver 

 and at the originating end, any one of a number of operators could 

 connect her telephone set to this circuit merely by depressing a key. 

 Let us assume, for example, that a call from New York to Philadelphia 

 is being handled by this trunking method. The customer in New 

 York has given the Philadelphia number to the New York operator. 

 The latter depresses a key which connects her telephone set to the 

 call-circuit which at Philadelphia is connected to the receiver of an 

 operator who handles only inward connections from New York. The 

 New York operator listens for a moment, to determine that no one else 

 is speaking on the call circuit, and then passes the Philadelphia number 

 over the circuit. Let us also assume that there are 50 toll circuits 

 between New York and Philadelphia, numbered 1 to 50. At the 

 moment that the New York operator passes the number to the Phila- 

 delphia operator, some of these circuits are in use. By glancing at 

 her switchboard the Philadelphia operator determines that circuit No. 



48 



