A performance monitoring system and method is based on a Detailed Call Record (DCR). A DCR contains records of events occurring in different network domains (14, 20, 40) that are related to a single, specific VoLTE call. The DCR events for each VoLTE call cover all legs of the call, and for each call leg, the relevant events are ordered by time. A DCR also contains basic information to identify the call: the IMS Charging Identifier (ICID), the International Mobile Subscriber Identity (IMSI) of all involved subscribers, and the start and stop timestamps of the call. A DCR has all the relevant user plane measurement, radio measurement, and control plane data from all the involved domains (14, 20, 40) for all call legs of a VoLTE call, in contrast to prior art systems that focus only on a single subscriber's activities for a given call. The DCR thus provides a complete view of the call, allowing more complete analytics and troubleshooting. Furthermore, the data are collected and assembled automatically, with results available real-time, or with a few seconds delay.