Erlang model is used for measuring the load on service providing equipment, such as telephone circuits or switches. This traffic engineering technique helps in determining the number of installations required in various telecommunication scenarios. One Erlang is equivalent to one call (including call attempts and holding time) in a specific channel for 3600 seconds in an hour. An Erlang symbolizes the continuous use of one voice path. Erlang represents the average number of concurrent calls carried by circuits. Outsourced call center companies make use of Erlang calculator to help in call center planning.

Erlang' calculators are used throughout the world to carry out a variety of statistical calculations associated with telecommunication systems and call centers. This method allows you to figure out how many agents are working and how much resources are actually required. This is calculated on Excel Spreadsheet.