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Collaboration, Voice & AV · Advanced

Erlang C

A queuing formula that estimates how many agents are needed to meet a service level when callers wait rather than being blocked.

Definition

Erlang C calculates the probability that a call waits and the average speed of answer given traffic in Erlangs and number of agents. It assumes infinite patience, so results may overstate staffing needs where abandonment is high. Workforce management tools build on Erlang C or simulation.

Example

Erlang C shows that 14 agents are needed to answer 80 percent of calls in 20 seconds.

Exam tip

Erlang C is the classic staffing formula for contact centers.

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