The process mining technique used by a Chilean Telecommunications Company to discover the source of failures in business processes in an automatic and efficient way is presented. Process mining is a set of business process management (BPM) techniques that helps analyze business processes using the event logs obtained from information systems that support the business processes. There are three types of analysis that could be conducted with process mining that includes process discovery, conformance checking and extension. Process discovery algorithms reveal the actual process from event logs. Conformance checking compares the event log against an a priori model of the process and the extension analysis allows identifying other useful information, such as bottlenecks, business rules or execution patterns. Business processes could be analyzed from different perspectives, such as control flow, organizational or time. PSDA allow discovering the sources of failures by analyzing the control flow perspective.