Abstract: Information on a connection status between a user equipment which accesses a core network of a communication net work system via a radio access network of the communication network system, and the core network is acquired (S21). From the information on the connection status it is determined (S22) whether or not data packets should be communicated between the user equipment and the core network. In case it is determined that data packets should be communicated, it is detected (S23) whether or not data packets are present on a user plane path between the user equipment and the core network. In case it is detected that data packets are not present on the user plane path, a silence report is generated and information on the detection result is indicated in the silence report (S24). Based on the silence report, a mute call between the user equipment and the core network is detected (S25).