Abstract: In an ISDN switching system, a program module is set up in accordance with the principles of object-oriented programming for the handling of switched connections. The protocol modules used in protocol architectures (for example CCITT recommendations) for the standardization of functional switching procedures are represented as object-oriented structural elements. During the implementation of the system program module in the switching system, objects are instantiated for connections and/or for calls and/or for signaling operations. A copy of the data area belonging to the structural element concerned is in each case set up in the data store as a kind of pattern. The data individual to the connection or call or signaling are entered into this pattern. The data areas remain in existence only for the duration of the connection or the call or the signaling operation concerned.