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How many minutes of traffic per day can a trunk group of 120 lines be offered if I accept that 2% of calls will be blocked and I estimate that 17% of daily calls are made during the busiest hour?

To find the answer to this question, carry out the following steps:

 • Select the Call Minutes Calculator using the tab control at the top of the window.
 • Click with you mouse on the radio button next to the Total traffic per day entry in the top section of the calculator. This indicated that it is the traffic quantity which you wish to calculate.
 • Enter 120 into the Number of lines edit box.
 • Enter 0.020 into the Blocking target edit box.
 • Enter 17 into the Busy hour factor edit box.
 • Press the Calculate button.

After a short time, the figure 37912 will be displayed in the Total traffic per day edit box indicating that 37912 minutes of traffic can be offered to the trunk group if a blocking figure of 2% is to be maintained and if the assumptions associated with the Erlang B traffic model are met.

With a busy hour factor of 19%, this traffic equates to 107.417 Erlangs (3867.012 C.C.S.) of busy hour traffic.