What is an Erlang?

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An Erlang is a unit of telecommunications traffic measurement.  Strictly speaking, an Erlang represents the continuous use of one voice path.  In practice, it is used to describe the total traffic volume of one hour.

For example, if a group of user made 30 calls in one hour, and each call had an average call duration of 5 minutes, then the number of Erlangs this represents is worked out as follows:

  • Minutes of traffic in the hour =             number of calls x duration
  • Minutes of traffic in the hour =             30 x 5
  • Minutes of traffic in the hour =             150
  • Hours of traffic in the hour =             150 / 60
  • Hours of traffic in the hour =             2.5
  • Traffic figure =             2.5 Erlangs