Due to the continued instability of domestic and international economic conditions in recent years, there has been an unceasing demand for measures to strengthen corporate competitiveness. In particular, customer service-centered call center operations are devoting their full efforts to developing human resource management strategies that can achieve organizational performance and competitive advantage through service delivery aimed at realizing customer satisfaction and delight. In line with this trend, the role of frontline employees—who communicate with customers at the point of contact and are directly evaluated based on outcomes—has become increasingly important. The importance of call centers continues to grow along with corporate growth, and accordingly, attention has been directed to the role of call center agents. The capabilities of call center agents can directly affect the interests of both customers and the firm, and depending on how agents perform their roles, they can actively retain and manage existing customers and increase customer loyalty to the firm. This study focuses on the emotional intelligence of individual agents who serve as the vanguard of new customer acquisition and marketing, and aims to examine the effect of emotional intelligence on agents' job performance. Additionally, the study seeks to verify the effects of organizational citizenship behavior—a voluntary helping behavior—and information technology (IT) utilization capability as essential tools during consultations on job performance, as well as to test whether these relationships differ according to work tenure. To test the proposed hypotheses, 564 questionnaires collected from professional agents at call centers of major domestic life insurance and property insurance companies were analyzed using PLS, and the results are summarized as follows. First, emotional intelligence had a significant effect on both organizational citizenship behavior and job performance. Additionally, IT utilization capability showed a significant effect on job performance, and organizational citizenship behavior was also found to be significant for job performance. Meanwhile, analysis of group differences by work tenure revealed that the effects of emotional intelligence and IT utilization capability on job performance, and the effect of emotional intelligence on organizational citizenship behavior, differed significantly by work tenure. In particular, the effect of organizational citizenship behavior on job performance was significant for the group with three or more years of tenure but was not significant for the group with less than three years of tenure. Research implications, practical implications, and future research directions are discussed based on the analytical results.