Unlike actual rainfall, the spatial extent of rainfall maps is often determined by administrative and political boundaries. Similarly, data from commercial microwave links (CMLs) is usually acquired on national basis and exchange among countries is limited. Up to now, this has prohibited the generation of transboundary CML-based rainfall maps despite the great extension of networks across the world. We present CML based rainfall maps for the first time, using independent CML data sets from Germany and the Czech Republic. For homogenization we apply three increasingly effective algorithms of filtering and time series interpolation. We show that straightforward algorithms used for homogenisation strongly reduce anomalies in the results. Furthermore, we find that after the homogenization and joint processing, CML-based rainfall maps can be generated which seamlessly visualize a rainfall event traversing the German-Czech border. This displays the potential for large scale (e.g. continental) CML-based rainfall estimation.