(EN) The invention relates to a method for supporting the mobility of a subscriber across a communication system (CSY) comprising a communication terminal (T1) which is associated with a first communication device (PBX1) 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 (PBX2) for providing configuration data of the subscriber, and a packet-oriented network (LAN) by which means the communication terminal (T1) is connected to the first and second communication devices (PBX1,PBX2). Once a successful registration has been carried out, the communication terminal (T1) is logged off the first communication device (PBX1) and associated with the second communication device (PBX2).