Evaluating erlang C and erlang A models for staff optimization: A case study in an airline call center

Call centers can easily be modeled as queuing systems where the calls arrive, wait in a virtual queue and are serviced by operators. The simplest representation of a call center is the M/M/N queue or the Erlang C model which in this study is tested on an airline call center. A further extension of the Erlang C model is the M/M/N+M queue or the Erlang A model which takes call abandonment into consideration, has also been evaluated and compared with the Erlang C and the simulation results. With the current system having a high number of abandoned calls, low number of agents and high utilization level, Erlang C estimates are markedly different to that of the real system and is pessimistically biased by a great extent. Erlang A predictions, on the other hand, although optimistically biased is a bit more accurate. The optimum staffing requirements for each model has been predicted.