Hearing aid configured to be operating in a communication system

The invention relates to a communication system comprising a hearing aid, a communication unit, a relay server, a rule processing server, and at least one external device, wherein the rule processing server comprises a data communication interface to communicate with said relay server and with a plurality of external devices over a plurality of data communication channels, a rule processor, and a rule base comprising a set of rules, each rule defining an action to be triggered in response to a trigger event. Said rule processor is configured to generate an action request signal in response to an event signal representing a trigger event. Said action request signal is configured to cause an action of at least one of the hearing aid, the communication unit, the relay server or the external device, and wherein said action request signal carries information that designates at least one of said devices and at least one action to be performed of said at least one device. Said communication system further comprises an event detector that is configured to detect a trigger event and to generate the event signal in response to a detection of the trigger event.