In order to detect unauthorized users of PINs, the OpenScape 4000 system has a trace mechanism. The OpenScape 4000 system always assumes unauthorized use if a user attempts to enter a PIN several times over (hacking). The maximum number of permitted consecutive mistakes/retries applies to all PIN types. The station number of the hacker station at which the PIN was attempted is output on the OpenScape 4000 service terminal, together with the date and time. If a PIN is already active, the station number of the home station is output. In addition, the last unauthorized PIN is printed out. This allows you to cancel a PIN if you detect or suspect unauthorized use within your system or domain. The station at which the hacker attempted to 'break' the PIN is not blocked.