DIALING HABITS OF TELEPHONE CUSTOMERS 



41 



period T the number of transits from state x to state x + 1 must equal 

 (or differ by no more than one) the number of transits in the reverse 

 direction. That is: 



nfix) = ^^/(.x + 1) 



(1) 



It may be noted that nh = a, where a is the average offered traffic 

 load in erlangs. 



1 2 34 5 6 7 8 9 10 1112 



TIME, t. IN SECONDS FROM START OF DIAL TONE TEST 



Fig. 6 — Results of dial tone tests. 



