Abandon rate

Abandonment is the demand that staffing models tend to miss, because Erlang C assumes callers wait indefinitely. Where abandonment is significant, Erlang C over-staffs — models such as Erlang A account for callers hanging up and return lower agent counts for the same service level.

A very short abandon threshold flatters the metric. Calls dropped in the first five seconds are often misdials or callers who changed their mind, which is why many centres report a 'short abandon' figure separately from genuine queue abandonment.

Abandonment is not purely a staffing problem. Queue messaging, position announcements and callback offers all change how long a caller tolerates waiting for the same underlying wait time.