Telecommunication systems are currently facing numerous technical and economic problems due to corrosion. Interface equipment (outdoor cross connection cabinets) includes the connection modules and their over-voltage protection magazines. These modules contain the connection terminals, which are permanently subjected to a direct voltage of 50 V and to a wide thermal range, with the consequent hot-house effect and corrosion, phenomenon that can lead to functionality problems. The connection terminals are made of brass coated with nickel and silver. One module contains 20 pairs of terminals. Each pair consists of two lead/terminal contacts in series. The resistance across each pair has been measured and from this value the lead/terminal contact resistance was deduced. Scanning Electron Microscopy with associated Energy X-Ray Dispersive Spectrometry (SEM/EDS) and X-Ray Diffraction (XRD) were used for morphological and chemical evaluation. With this work it was possible to characterize the connection terminals and to evaluate the formed corrosion products in laboratory and in real exposure conditions. Analysis and treatment of obtained data allowed to conceive and to propose a simple model to explain the observed evolution of the contact resistances during artificial ageing in cabinet.