Purpose - The purpose of this paper is to develop an enhanced framework for workforce management in a modern call center environment, called the consecutive staffing using simulation (CSS) approach. The paper aims to investigate the value of a time-dependent approach to determine staffing levels without making an assumption that call centers to be a queuing model in a steady state. Design/methodology/approach - Staffing is usually accomplished through the use of simple queuing models, Erlang-C (M/M/c). It is common to adopt a stationary independent period by period (SIPP) approach. However, staffing based on SIPP does not consider uncompleted calls and each planning interval cannot achieve a steady state in most cases, since the lengths of planning intervals are short in fact. In this context, the CSS approach considers uncompleted calls and determines staffing levels by using simulation. Findings - Staffing based on the CSS approach needed fewer agents, compared with staffing based on the SIPP approach. Hiring less agents during a single planning horizon lead to a decrease in total operational costs for the call center. Staffing based on SIPP became less accurate when the average service duration became longer or the arrival rate fluctuation was large, which often occurred in the morning and around lunch break. Originality/value - The CSS approach is based on the dynamic staffing proposed by Whitt. However, CSS extends the basic idea of dynamic staffing to combine a simulation experiment with a number of repetitions and the same run length of planning intervals. In a call center with shorter planning intervals, management should adopt staffing based on CSS for accurate planning and updating of staffing levels during a single planning horizon.