A design of a particular Information System (IS) incorporating characteristics of an MIS (Management Information System) and DSS (Decision Support System) is presented. The IS designed includes an MIS and DSS integration. The paper is mainly concerned with the management of a telecommunication network, emphasising maintenance engineering aspects of the network. Therefore, a MMIS (Maintenance Management Information System) is designed, integrated with the project and construction (or installation) functions of the system. The application was designed to support the private Telecommunication System of an electricity company. The approach followed recommends a way of developing the planning of IS through a participating methodology. The first stage of this methodology is the strategic planning, followed by the data, process and organisation analysis. An Information Engineering step concludes the modularisation and prioritisation of the whole IS. The application of the methodology shows that users can realize and accept the advantages cf the corporate aspects of the IS having a greater commitment to the project when directly involved in the design of the IS. Further results show that the use of operational research and statistical techniques can become more effective by the implementation of this kind of IS, as supported by other studies.