The invention relates to a plurality of common switching systems which are interconnected in order to form a virtual switching system. The number of the internal switching system is entered into the numbering of the port of the virtual switching system thus making a standardized user interface of the switching system become available. The port can be managed by a user in a traditional manner. The virtual switching system can be automatically configured due to said type of configuration when a central entity for developing the internal routing on the partial system is introduced, and then, optional geographical redundancy of the virtual switching system is possible.