Since 2017, the Passenger Division at the Swiss Federal Railways has used MATSim as the main framework for SIMBA MOBi - its activity and agent-based transport model. By now, SIMBA MOBi is a well-established model that helps the company’s decision-making process in passenger demand planning. Very early in the development stage of the model SBB has committed itself to contributing actively in the MATSim core libraries under GPL. In this talk, we briefly give an overview about the model itself, its applications and SBB’s long-standing contributions in MATSim. We also point out the advantages and limitations of using an academic open source software in our active production environment. MATSim is available under GPL and its code repository is https://github.com/matsim-org/