Devices and method for guaranteeing quality of service per service data flow through the bearer layer

In scenarios where the quality of service is negotiated through a signalling layer whereas the services are actually carried through a bearer layer, application functions at the signalling layer are not always aware of how quality of service is individually accomplished at the bearer layer on a service basis. The invention provides a method and devices whereby events are detected on a service data flow basis at a detection device in the bearer layer and notified towards an application device in the signalling layer via a control device between the signalling and the bearer layer. The list of events to be notified is obtainable at the control device from the application device and is included in Quality of Service related rules, along with service data flow filters. This Quality of Service related rules are provided to the detection device for inspecting individual service data flows in order to detect and notify the indicated events.