The nurse rostering problem, which addresses the task of assigning a given set of activities to nurses without violating any complex rules, has been studied extensively in the last 40 years. However, in a lot of hospitals the schedules are still created manually, as most of the research has not produced methods and software suitable for a practical application. This paper introduces a novel, flexible problem model, which can be categorized as ASBN|RVNTO|PLG. Two solution methods are implemented, including a MIP model to compute good bounds for the test instances and a heuristic method using the simulated annealing algorithm for practical use. Both methods are tested on the available benchmark instances and on the real-world data. The mathematical model and solution methods are integrated into a state-of-the-art duty rostering software, which is primarily used in Germany and Austria.