CENTRALIZED AUTOMATIC MESSAGE ACCOUNTING SYSTEM 1337 

 FUNCTIONS OF THE CAMA SYSTEM 



The functions of the system in establishing a connection and in re- 

 cording the billing data may be divided into seven major groups as 

 follows : 



1. Operation of the sender link and control circuit in selecting an idle 

 sender and connecting the selected sender to the incoming trunk. 



2. ReceiAdng and registering the called office code and number in the 

 sender. The sender does not pulse the entire number forward until the 

 Aj\IA functions are completed. 



3. Operation of the marker in establishing the connection through the 

 switches and furnishing the sender with directions for completing the 

 call. 



4. Operation of the position link and control circuit in selecting an 

 idle occupied position and connecting it to the calling customer. 



5. Obtaining the number of the calling telephone verbally from the 

 customer and keying it into the sender. 



6. Connection of the sender to a transverter and billing indexer and 

 the derivation of the billing data from the called and calling office codes 

 and the rate class of the calling customer, and recording the charging 

 information on the AM A tape. 



7. Operation of the sender in transmitting information of the proper 

 type to the terminating office, or if a toll call, to the next toll office in the 

 chain. 



Calls from Panel and Crossbar Customers 



The first three functions in a crossbar tandem CAMA-equipped office 

 in a panel-crossbar area are the same as in a non-CAMA office. Since 

 published information on these features is available, they will not be 

 described in detail. 



The fourth major function is handled by the position link and control 

 circuit which is sho^Nii in block diagram form in Fig. 4. This circuit con- 

 sists of primary and secondary crossbar s^^atch links and control circuits 

 in duplicate. Each group functions independently to serve calls to the 

 same 40 senders and can connect to two different groups of 50 positions. 

 In case of failure of one link group, the other link group ■u'ill continue to 

 serve calls to the 40 senders. The control circuits are arranged in such a 

 manner that all senders and all positions receive essentially equal treat- 

 ment. 



WTien the position link connects the sender to an idle CAMA position, 

 the operator obtains the calling number verbally from the customer and 



