nsists of three main steps: detection of the faulty cells; analysis and diagnosis of potential origins for the problem; application of the estimated solution. Automation can be applied to all three phases. Detecting faulty cells can be done using preestablished cri- teria and thresholds on the basis of comparison against some restrictive conditions. The main idea behind automatic diagnosis is the transfer of experts' knowledge to the system. To achieve this, troubleshoot- ing models should be created and corrected. Modelling means equipping the machine with adequate reasoning algorithms to help it find out the possible origin of the problem and propose eventual solutions. Location Area Planning To inform a subscriber about an incoming SMS or call, the network uses paging to all BTSs of a given LAC. Location area planning consists of finding the appropriate size of LA in order to ensure that paging success is maximised and the number of location updates (LUs) is minimised. Paging success decreases due to deleted paging messages in the case of a very large LA. On the other hand, paging load increases due to the high number of LUs in the case of a too small LA. It is also worth noting that the capacity of an SDCCH is much lower than that of the PCH. Thus the aim of the automatic method is to establish the correct balance by defining the correct LA size. Operators traditionally use one of two approaches for LA planning: Turning each BSC into an LA, in which case a huge amount of LU takes place due to inter-BSC handovers (note also that mobiles in the idle mode perform LU). This approach consumes much SDCCH resource. Turning each MSC area into an LA, in which case the paging load goes up, with the result that some mobiles are not informed about incoming calls or SMS. This approach saves the signalling resource, but still does not properly consider the actual capacity of the paging channel. The main idea behind Automated Location Area Planning is to use Network Management System (NMS) data to fix an optimum LA size. El