1336 THE BELL SYSTEM TECHNICAL JOURNAL, NOVEMBER 1954 



information necessary for correctly charging for the call will then be re- 

 corded on paper tape by the automatic message accounting equipment 

 located in the tandem office. This method of operation is sho\\n in 

 simplified form on Fig. 2. 



A more detailed block diagram of the principal eciuipment units and 

 their interconnections for a crossbar tandem CAMA office in a panel- 

 crossbar area is shown in Fig. 3. Here the switching equipment consists 

 of the conventional trunks, sender link frames, senders, markers and 

 trunk link and office link frames for switching calls through the office. 

 Such new iniits as the position link frames, positions, transverters, billing 

 indexers, recorders, call identity indexers, and master timer constitute 

 the major AM A equipments needed for recording the billing information 

 for each call. Most of these have functions similar to corresponding local 

 AMA equipments. AMA features have also been added to the trunks, 

 sender links and senders. 



TRUNK LINK FRAME 



OFFICE LINK FRAME 



FROM 



PANEL OR 



CROSSBAR 



CENTRAL 



OFFICE 



INCOMING 

 TRUNK 



SENDE_R_UNK 



CONTROL 

 CIRCUIT 



PCI 

 SENDER 



CALLING NO. 

 REGISTER 



POSITION LINK 

 CONTROL CIRCUIT 



OUTGOING 

 TRUNK 



l^-' 



THRU 

 - MARKER 

 CONNECTOR 



\THRU 



TRANSVERTER 



CONNECTOR 



TRANSVERTER 



BILLING 

 T I INDEXER 



1:^ THRU 

 CONNECTORS 



RECORDER 



MASTER 

 TIMER 



CALL 



IDENTITY 

 INDEXER 



Fig. 3 — Block diagram of CAMA system in panel -crossbar areas. 



