The invention relates to a method for supporting the mobility of a subscriber across a communication system comprising a communication terminal which is associated with a first communication device and can be registered when a log-on procedure is initiated by the input of log-on information relating to the subscriber, a second communication device for providing configuration data of the subscriber, and a packet-oriented network by which means the communication terminal is connected to the first and second communication devices. Once a successful registration has been carried out, the communication terminal is logged off the first communication device and associated with the second communication device.