A computer implemented method of operating a base station of a wireless communication network, wherein the method comprises: comparing a number of missing context release messages (108) with a first criterion; —comparing the error rate of connection reestablishment messages (112) with a second criterion; executing a cell global identity search algorithm (110) if at least one of the first and the second criterion is fulfilled, wherein the cell global identity of at least one cell with the physical cell identity of the cell where the criterion was fulfilled is requested via an automatic neighbor relation measurement, and wherein a conflict of physical cell identities is detected and reported to an information algorithm (116) when for the physical cell identity at least two cell global identities are found; —an information algorithm for informing a central network element (118) and/or at least one base station (120) of the mobile communication network about a conflict of physical cell identities when a conflict of physical cell identities is reported to the information algorithm; and —initiating a reassignment of at least one physical cell identity.