When companies design communications networks, they consider how much traffic they expect. The BHCA - busy hour call attempts - represents the average number of times per hour each subscriber tries to make a call. Higher BHCAs strain network processors. Calculate BHCA using subscribers' usage data.
Multiply a subscriber's monthly minutes of usage by the percentage of traffic that occurs during working days. For instance, if a subscriber talks for 500 minutes in a month, and 80 percent of calls occur during the work week:
500 X 0.80 = 400
Multiply your answer by the percentage of voice traffic that occurs during the busy hour. For instance, if 10 percent happens during the busy hour:
400 X 0.10 = 40
Divide your answer by the number of working days per month. If each month contains 20 working days:
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40 / 20 = 2
Divide your answer by 60.
2 / 60 = 0.0333.
This answer shows your phone traffic in Erlangs, a unit that represents hours of usage per subscriber per busy hour.
Multiply the answer by 3600.
0.0333 X 3600 = 120
Divide the answer by mean holding time, in seconds. If your mean holding time is 80 seconds:
120 / 80 = 1.5
This answer is your BHCA.