Abstract: In order to establish data links between differently structured subscriber stations, a central modem (modem pool) is inserted. When setting up connections for which a central modem is to be inserted, service indicator information in conformity with the relevant ISDN protocol is formed which designates the service implemented on the destination side by the inserted modem.

Abstract: Method for the visualization of logged information in a communication system. With the assistance of an administration and maintenance program module (trace program module), the logged information is respectively formed by code words (KW) logging a program step during the execution of switching-oriented programs utilized in a communication system. With the assistance of the method, those code words (KWS) that were logged during the execution of prescribed originating and prescribed destination programs are selected. Prescribed terms of the selected code words (KWS) are converted into mnemonic information (pi, zn, un, zsn, mn) and displayed at a display means. Further, the directional information (rn) indicating the internal message flow and the message flow between the programs is formed and graphically displayed at the display means. The interpretation of the logged information is thereby considerably simplified.