Railways currently use the Global System Mobile for Railways (GSM-R) for train operation across the world. The GSM-R is used for voice communication between train driver and control centres, including but not limited to, the Railway Emergency Call (REC) as well as for signalling and control messages of the European Train Control System (ETCS). Based on the fifth generation (5G) of mobile networks and in particular, 3rd Generation Partnership Project (3GPP) releases 17 and 18, the Future Railway Mobile Communication System (FRMCS) is envisioned to replace GSM-R. This modernization step does not only address administrative constraints, e.g., the upcoming 2G equipment obsolescence, but also provides an opportunity for transforming the current train operation through introduction of digitalization and automation technologies in an aim of increasing capacity and efficiency for a sustainable transport. In this paper, we present some highlights of first FRMCS Fields trials that have been realized within the 5GRAIL project which is funded by the EU Horizon 2020 program. These trials were co-led by DB Netz AG in Germany and SNCF RESEAU in France. The aim was to accomplish functional and performance testing in addition to multi-access and cross-border like scenarios. We discuss some results on the testing of the different applications before concluding with lessons-learned and outcomes.