# Abandon rate

The abandon rate is the percentage of the total volume that is abandoned.

Define the abandon rate when creating a telephony or chat skill. The entered abandon rate is used in the Erlang A model to estimate the callersâ€™ average patience, which is the average time that a caller will stay in the queue before abandoning the call. This is then used while forecasting the number of agents needed and the predicted service level.

Analyze what the abandon rate is at times when the service level is reached or when it is acceptable. Enter that abandon rate in the skill properties. Do not use the average abandon rate.

Possible values for the abandon rate are between 0%-30%. If you use an abandon rate of 0%, that means that the forecast is created based on the assumption that no one will leave the queue. This gives the same result as using the Erlang C model.

The predicted abandon rate for the current staffing levels is in the result table in the Schedules module. For further information, see Understand the result table parameters.

IMPORTANT Use the abandon factor with caution. Start with very low values and adjust upwards, if needed. An abandon rate that is too high will negatively impact the staffing calculations.