COMMON CONTROL SWITCHING SYSTEMS I I I I 



ADVANTAGES OF COMMON CONTROLS FOR AUTOMATIC UECOUDING OF IN- 

 FORMATION FOR CHARGING 



The crossbar tandem system offers an economical method tor makiiiji; 

 a record for charging i)uri)osos on mnlti-unit bnlk billed calls called re- 

 mote control of zone registration. At present this is limited to use with 

 oiiginating panel offices. The tandem is arranged to send back signals to 

 the originating office for operating the customer's message register u]) to 

 six times for the initial period on one call and also to operate it on over- 

 time. Thus the application of extended customer dialing can be eco- 

 nomically increased b}^ apphnng this arrangement in places which cannot 

 justify the registration ari'angements available in the panel system itself 

 which are economical only for a relatively heavy volume of this business. 

 Local crossbar sj^stems provide these features economically enough to 

 obviate the need for tandem control of message registers for calls orig- 

 inating in the crossbar offices. 



When tandem offices are required to control the equipment which 

 lecords customers' charging data, they must be equipped with common 

 controls if the arrangement is to be economical. The data includes the 

 origin of the call — the particular trunk group incoming to tandem over 

 which the call arrives — and the destination — the called office code. These 

 elements must be analyzed and combined to determine the basis for the 

 amount charged. Since elaborate equipment is required for these func- 

 tions, economy must be attained by providing a minimum amount of 

 equipment to do the job. This objective is accomplished by providing the 

 re(iuired features in the common controls. In tandems arranged for re- 

 mote control of zone registration, for example, the number of times the 

 customer's message register is operated is determined partly by the 

 choice of trimk group at the originating office and partly by the tandem 

 markers. 



In addition to remote control of zone registration, there are several 

 other methods of determining and recording charging data which also 

 re([uire the use of common control equipment. These are automatic 

 ticketing, automatic message accounting and coin zone dialing. 



In automatic ticketing, which is used with step-by-step systems, calls 

 which are to be ticketed are directed to outgoing trunks which select 

 senders and other common equipment which determine the calling line 

 number, reconstruct the called office code and store and outpulse the 

 digits required for selections beyond the local office. The calling line 

 number and the called office code are transmitted by the common equip- 

 ment to the outgoing trunk which is equipped with a ticket printing 



