A networked probe system for a communications network (28) comprising at least one user device and at least one network device, comprises a plurality of probes (25). A probe (25) is provided in each path between the or each user device and the or each network device. Each probe (25) stores one or more parameters of interest. The probes (25) monitor communication from the user device for a subset of the communication satisfying the one or more parameters. On determining the presence of the one or more parameters in the subset of the communication, the probe (25) provides a notification to all other probes in the network (28).