ITU-T E.436

This Recommendation addresses outages that result in Customer Affecting Incidents (CAI) and relates them to the call blocking Defects Per Million (DPM) metric for the switched network. It is discussed that these outages affect both the customers and the service provider in a significant manner. Definition of what constitutes a Customer Affecting Incident is presented. A methodology for tracking Defects Per Million metric is developed along with a recommended method for Root Cause Analysis. There are various parameters for exchanging network performance results among Administrations. CAI and DPM are additional performance parameters that may be exchanged to take network improvement actions.