16 December 2025

Ericsson has partnered with Switzerland’s national rail operator, SBB (Schweizerische Bundesbahnen), to deliver Europe’s first live integration of legacy railway communication systems with a modern IP Multimedia Subsystem (IMS) platform supporting Voice over LTE (VoLTE).

This groundbreaking upgrade ensures continuous, reliable communication across Switzerland’s 3,100 km rail network, ahead of Swisscom’s planned decommissioning of 3G services by the end of 2025. The project also includes onboard 4G enhancements for approximately 1,000 trains, significantly improving connectivity and operational reliability.

For years, Swiss rail voice communication relied on Swisscom’s 3G network in areas lacking GSM-R coverage. With Swisscom’s decision to phase out 3G, SBB faced an urgent need to modernise its network. Rather than expanding the aging GSM-R system, SBB enlisted Ericsson to develop a future-proof solution based on IMS and VoLTE technology, seamlessly bridging traditional rail-specific functions with contemporary mobile and fixed telephony systems.

Ericsson successfully designed and deployed the integrated solution, combining multiple vendor technologies into a converged IMS core. This system guarantees continuous, end-to-end communication for safety-critical operations, establishing new standards for railway modernisation across Europe. The deployment prioritised zero service disruptions and strict safety compliance, including features such as IMS-GSM-R interworking, GSM-R numbering adaptation, emergency stop calls, group calls, and onboard announcements.

This modernised infrastructure ensures high-performance rail communication, reducing risks associated with legacy systems. Importantly, key rail-specific functions — including the European EIRENE radio network, emergency stop calls, group calls, and onboard announcements — are preserved and seamlessly integrated. The upgrade also lays the groundwork for future 5G and FRMCS (Future Railway Mobile Communication System) innovations, supporting Switzerland’s transition to next-generation railway communication standards.

“Our collaboration with SBB demonstrates our ability to deliver complex digital transformations within tight timelines. We are proud to set new benchmarks in railway communication and support the ongoing transition to FRMCS,” said Nicolas Segond, Head of Mission Critical Communications for Railways at Ericsson.

As the project progresses toward full migration by December 2025, the insights and experience gained will inform similar railway modernisation efforts worldwide, ensuring safer, more reliable, and future-ready rail networks.