Patent ID: 7668133

Claim:
A presence server unit comprising: a manager which is designed to manage presence information relating to the availability of a communication unit; a receiving device which is designed to receive a message from each checking unit of a plurality of checking units, which message specifies that, when the presence information is changed, change information relating to the change to the presence information should be transmitted to the respective checking units; a memory in which priority information is stored, which priority information is information relating to a notification ranking on the basis of which the change information should be transmitted to the plurality of checking units and which is contained at least partially in the message received from one checking unit of the plurality of checking units, with the priority information which is contained in the message which is received from the checking unit of the plurality of checking units specifying that the change information should be transmitted to this checking unit before the change information is transmitted to the other checking units in the plurality of checking units; and an information device which is designed to transmit the change information, when the presence information is changed, in accordance with the notification ranking to the plurality of checking units.