Swisscom

Switzerland’s SBB has deployed an Ericsson IMS/VoLTE platform that interworks with legacy GSM-R, delivering Europe’s first live bridge between public 4G voice and mission-critical railway communications. Ericsson and SBB completed a nationwide IMS/VoLTE integration that extends reliable voice communications across Switzerland’s 3,100 km rail network and removes dependency on public 3G roaming for coverage gaps outside GSM-R footprints. The IMS core integrates multi-supplier elements and preserves EIRENE features such as functional numbering, group calls, emergency stop calls, and onboard announcements, ensuring safety-critical behavior is maintained. It also demonstrates that mission-critical requirements can be met over modern IP telephony when engineered with the right interworking, governance, and testing.