Agner Erlang, born in 1878 in Denmark, pioneered the study of telecommunications traffic and developed a formula to model waiting times for telephone calls. Call center managers named several traffic models after the Danish statistician. The Erlang C model allows you to determine the number of agents you will need during any given hour based on the number of calls your center receives, their average duration, including wrap-up time, and the acceptable delay in answering them.
Pull weekly and hourly call volume statistics for the past four weeks. Review total call volume trends to predict traffic for a given day. Break the expected call volume for the day into hourly predictions.
Review agent performance statistics and determine the average amount of talk time per call as well as the average amount of wrap-up time an agent spends on follow-up work after the caller releases. Compare those statistics with goals to gauge agent performance versus expectations.
Enter the average call duration, wrap-up time, and hourly call statistics into an Erlang C calculator. Calculators available online offer different degrees of specificity in running the Erlang C model. Depending on your workforce needs, you can calculate average delay time and agents needed for the day or for the hour. You can also calculate the degree of improvement in agent performance that is necessary to meet your goals.