Prepaid customers in mobile telecommunications are not bound by a contract and can therefore change operators (‘churn’) at their convenience and without notification. This makes the task of predicting churn both challenging and financially rewarding. This paper presents an explorative, real world study of prepaid churn modeling by varying on three dimensions: data, outcome definition and population sample. Firstly, we add Customer Experience Management (CEM) data to data traditionally used for prepaid churn prediction. Secondly, we vary the outcome definition of prepaid churn. Thirdly, we alter the sample of the customers included, based on their inactivity period at the time of recording. While adding CEM parameters and varying the sample did not influence the predictability of churn, a particular change in the outcome definition had a substantial influence.