Ericsson completed Europe’s first large-scale integration of GSM-R with an IP Multimedia Subsystem (IMS) and VoLTE platform for Swiss national rail operator SBB, creating a future-proof communications system ahead of Swisscom’s 3G shutdown at the end of 2025. The upgrade spans Switzerland’s 3,100-km rail network and replaces legacy roaming dependencies with a nationwide, fully modernized voice architecture. The deployment also includes onboard 4G service upgrades for roughly 1,000 trains, strengthening operational reliability for one of Europe’s busiest rail systems.
The project eliminates SBB’s historical reliance on Swisscom’s public 3G network to fill GSM-R coverage gaps, which would have become unsustainable after 2025. SBB selected Ericsson to deliver a converged IMS core that maintains GSM-R-specific features while enabling VoLTE across the fleet. Ericsson integrated multi-vendor technologies and conducted a multi-year test program beginning in mid-2023, culminating in a national go-live in April 2025. As of December 2025, the system supports approximately 450 trains and 1,000 operational devices with zero downtime reported.
The migration preserves all rail-critical functions—including EIRENE numbering, emergency stop and group calls, and onboard announcements—while preparing the network for FRMCS and 5G rail corridor deployments. Ericsson’s phased rollout emphasized safety compliance, uninterrupted operations, and intensive training for SBB teams. Lessons learned are expected to inform future railway modernization programs across Europe as operators transition away from legacy GSM-R and public-network co-dependencies.
• First nationwide IMS/VoLTE integration for railway operations in Europe
• 3,100-km Swiss rail network supported with mission-critical voice continuity
• 1,000 trains upgraded for onboard 4G; ~450 trains already using VoLTE
• Interworking functions include GSM-R numbering adaptation, emergency stop calls, group calls
• Multi-vendor IMS core ensuring end-to-end communications resilience
• Key milestones: Deployment (Jun 2023), first VoLTE–GSM-R calls (early 2024), field certification (Jan 2025), national go-live (Apr 2025)
• Supports FRMCS readiness and eliminates dependence on public 3G networks
• Zero-downtime transition with extensive SBB operational training programs
“Our work with SBB demonstrates our capability to deliver complex digital transformations under tight timelines. We look forward to setting benchmarks in railway communication innovation and supporting the transition to FRMCS in the coming years,” said Nicolas Segond, Head of Mission Critical Communications for Railways in Europe, Middle East and Africa at Ericsson.
🌐 Analysis: European rail operators are accelerating their transition away from GSM-R as public networks retire 2G and 3G services. Switzerland’s early IMS/VoLTE deployment positions SBB as a model for FRMCS migration while showcasing Ericsson’s capabilities in mission-critical communications. Similar modernization efforts are underway in Germany, France, and the Netherlands, though Switzerland is currently the only nation with a nationwide IMS-VoLTE rail integration in live service.
