What do you mean by Erlangs?

Erlangs:

1) Total traffic volume per hour / 3600 seconds is described by erlang
2) 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