That ultimately depends on your objectives and call center type (inbound/ outbound). For example, inbound call centers that mostly deal with incoming inquiries would want to measure customer service-related Key Performance Indicators (KPIs) and metrics like the average handling time (AHT), first call resolution rate (FCR), call transfer rate, call abandonment rate, customer satisfaction score (CSAT), and others. Alternatively, outbound call centers would typically want to measure call answer rate, dropped call rate, conversion rate, first call close, cost per call, and other outbound-related metrics.