★ Total traffic volume per hour / 3600 seconds is described by erlang

★ For example, 60 calls in one hour and each lasting 5 minutes results the following:

Minutes of traffic in an hour = Number of calls x Duration

Minutes of traffic in an hour = 60 x 5 = 300 minutes

Hours of traffic in the hour = 300 / 60 = 5 hrs

The traffic figure = 5 erlangs