DIALING HABITS OF TELEPHONE CUSTOMERS 



49 



o40 



z30 



<30 



30 40 50 60 70 80 90 10 20 30 40 



PER CENT DIAL TONE DELAYS GREATER THAN 3 SECONDS 



Fig. 7 — Average customer waiting time (H). 



50 60 70 



tially the effect of occasionally having two or more calls waiting on one 

 trip circuit sub-group. The rules and the reasons for them will be de- 

 scribed with the aid of Fig. 8, which shows a hypothetical section of 

 one of the tapes. The rules were as follows: 



1 . Initial Overlap 



Referring to Fig. 8, at ti a subscriber has initiated a request for 

 service. At t-y a line finder rises to serve the subscriber. At tz the sub- 

 scriber receives service. This case is typical of a subscriber receiving 

 prompt dial tone service. 



The span from ^i to ti was difficult to measure accurately because, 

 for the usual case, it was about the same as the maximum error due to 

 misalignment of the recorder pens. It w^as not measured unless the com- 

 bined span from ti to ts exceeded one second. 



The span from ^2 to ts involves an overlap, it represents a period 

 when a line finder is busy hunting for the terminal of the subscriber who 

 originated the request for service. It also represents a period when a 

 subscriber is waiting for service. In the analysis this span was treated 

 as a case where a line finder was busy with a call and not as a call wait- 

 ing for service. 



If the span from ^2 to ^3 and all similar cases had been treated as 

 calls waiting for service and if in addition all spans from ti to ti which 

 were not measured had also been treated as calls waiting for service, 

 the average values for H would have increased slightly for each class 

 of service. 



