Abstract: The invention relates to an information system for a PABX (1) having extensions (B1-B5), a switchboard (2) for manual switching operations, and a direct inward dialling (DDI) function for switching calls provided with a DDI code directly to the PABX extensions. In the invention, the majority of incoming calls to the PABX are controlled by the information system of the invention, which comprises a database (21) maintaining status information on PABX subscribers, and a central processing unit CPU (20) connected to the database and to a voice message unit (22) controlled by the CPU on the basis of status information retrieved from the database, to deliver the desired voice messages to the calling party.