Centralized Automatic Message 

 Accounting System 



By G. V. KING 



(Miinuscript received May 6, 1954) 



A centralized automatic message accounting si/stem. (CAM A) has been 

 (Jrveloped so that the hilling data can be recorded at a centralized crossbar 

 tandum office for message unit and toll calls originated by telephone customers 

 served by a large number of local dial central offices. It is an essential part 

 of facilities for economical nationwide customer dialing through central 

 offices with older types of switching equipment and through other central 

 offices which could not otherwise economically give this service. The new sys- 

 tem records the billing data on paper tapes in the same form now used by 

 local automatic message accounting systems. Tapes for both local and cen- 

 tralized automatic message accounting systems are processed in the same 

 accounting center. 



INTRODUCTION 



One broad objective of the Bell System is to extend the customer's 

 dialing range so that ultimately he will be able to dial his own calls to 

 any telephone in the country in much the same way as he now dials local 

 calls. Several steps toward this goal have already been taken. A revised 

 fundamental plan for automatic toll switching has been adopted which 

 involves among other things the use of a nationmde numbering plan 

 covering the United States and Canada. In accordance with this plan 

 each customer will be given a distinctive 10-digit designation which will 

 consist of a 3-digit regional or area code, a 3-digit central office code, and 

 a 4-digit customer's number. In many parts of the country automatic 

 toll switching systems are now in use by operators who complete more 

 than 40 per cent of all toll calls by dialing directly to the called telephone 

 in distant cities. 



In order that customers may use these switching systems to dial their 

 own toll calls, some automatic means for recording the necessary billing 

 information on such calls must be provided. 



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