Erlang (Er) is a unit of telecommunications traffic measurement that represents the continuous use of one voice channel or the total traffic volume of one hour. For example, if a group of users made 30 calls in one hour and each call had an average duration of 5 minutes, then the traffic figure is 2.5 erlangs.
Erlang is used to estimate the number of lines, trunks, or servers needed to handle a given amount of traffic, based on various traffic models and formulas. Erlang is also used to monitor and evaluate the performance and quality of service of telecommunications networks, based on various key performance indicators and metrics.
To calculate Erlang for a given traffic volume, you need to know the number of calls and the average duration of each call in one hour.
Then, you can use the following formula:
Erlang = (number of calls x average duration in minutes) / 60
For example, if you have 100 calls in one hour, and each call lasts 3 minutes on average, then the Erlang is:
Erlang = (100 x 3) / 60
Erlang = 300 / 60
Erlang = 5
This means that the traffic volume is equivalent to 5 voice channels being used continuously for one hour.