Abstract: Apparatuses and methods providing indications of service failure in a communications network. At least one N-dimensional vector of key performance indicator values is acquired from at least one network equipment device. An outlier score is determined for the at least one N-dimensional vector by using an L-valued outlier scoring function based on N-dimensional regions Rk, k=1, L, where L>1, and where region Ri is at least partly enclosed by region Rj, and where the outlier score for the N-dimensional vector is dependent on in which of the N-dimensional regions Rk the N-dimensional vector is located. An indication of service failure is determined for the at least one network equipment device based on the outlier score for the at least one N-dimensional vector.