A method performed by a network node for deciding a probability that a first User Equipment, UE, is located in a building is provided. The network node, the first UE and one or more second UEs operate in a wireless communications network. The network node learns (203) that one or more second UEs are associated to a respective subscription comprised in a group of subscriptions related to the building. The one or more second UEs are decided to be located in said building. The network node identifies (204) cell relation metrics for the one or more second UEs associated to the group of subscriptions. The cell relation metrics relate to the building. The network node then decides (206) the probability that the first UE is located in the building, based on to what extent a cell relation metric of the first UE matches the identified cell relation metrics for the one or more second UEs.