Switzerland’s Rail Network Pioneers First Live VoLTE Integration for Railways

Published on December 29, 2025

Swiss Federal Railways (SBB), and Ericsson are implementing the final stages of a technology transition that upgrades the railway communications system in the whole country. The update will modify the railway network’s obsolete communication system to the current mobile standards. The new communication system will guarantee uninterrupted voice and data connections for rail/trains before the public 3G networks are shut down in 2025. This is the first live railway telecom migration in Europe, making it possible to provide reliable communication for one of the busiest transport systems in Europe.

Why the Upgrade Matters

Swiss Federal Railways operates one of Europe’s most extensive rail networks, transporting millions of passengers and freight every year. Historically, train voice communication relied on GSM‑R (Global System for Mobile Communications – Railway), a technology specifically designed for rail use. Where GSM‑R signals were weak or unavailable, trains used roaming on Swisscom’s public 3G network to maintain critical communication.

Swisscom plans to shut down its 3G services by the end of 2025. Without modernisation, SBB risked losing voice coverage on parts of its routes when that network goes offline. To prevent service gaps, SBB partnered with Ericsson to shift train telecommunications from GSM‑R/3G reliance to an IP‑based platform using IMS (IP Multimedia Subsystem) with VoLTE (Voice over LTE).

What Changed in the Technology

The project connected the existing GSM‑R framework to a modern IMS core that supports VoLTE voice services over 4G and prepares for future 5G compatibility. This means trains now communicate securely and continuously using updated mobile standards. The solution also includes onboard 4G upgrades across approximately 1,000 trains, improving reliability and enabling higher data performance for operational communication.

Key technical shifts include:

• Replacing public 3G roaming dependency with integrated IMS/VoLTE infrastructure.
• Connecting legacy GSM‑R radios with modern LTE voice systems.
• Preserving safety‑critical features such as emergency calls, group calls and rail‑specific numbering.

How the Rollout Progressed

The transition followed a structured deployment and testing plan spanning over two years. Main milestones:

• Mid‑2023: Work began connecting GSM‑R with the IMS core.
• Early 2024: Initial calls between VoLTE and GSM‑R systems proved successful.
• January 2025: Field tests expanded to real trains, certified by Switzerland’s transport regulator.
• April 2025: Nationwide go‑live achieved well before the 3G shutdown deadline.

By late 2025, the upgraded system was carrying communications for about 450 trains and 1,000 operational devices using VoLTE technology with no reported service interruptions.

What This Means for Rail Operations

The new system ensures that voice and data links remain stable during rail journeys across urban and rural areas, even after 3G services disappear. Trains and control centres communicate using modern mobile standards without compromising safety or functionality. The platform supports essential rail operations and is ready for further evolution toward 5G‑based Future Railway Mobile Communication System (FRMCS) standards, expected to replace GSM‑R entirely over the coming decade.

Guide for Travellers

If you plan to travel on Swiss trains soon, here’s what the modernisation means for you:

1. Reliable Onboard Communications

Voice communications between train staff and control rooms are now supported by updated mobile technology, ensuring safety messages and operational instructions remain constant.

2. Improved Service Continuity

Train operations won’t experience service gaps even as public 3G networks are decommissioned. The transition to IMS/VoLTE guarantees that control systems stay connected nationwide.

3. Better Connectivity Coverage

By using upgraded networks that combine GSM‑R and VoLTE, trains can maintain links even in areas where traditional rail signals were weak. This supports scheduling reliability and helps prevent delays caused by communication issues.

4. Future‑Ready Rail Travel

The current upgrade lays groundwork for future enhancements like 5G‑based communication systems, which may enable more advanced passenger services and operational tools in the future.

Broader Impact and Lessons

Swiss Federal Railways’ telecom upgrade serves as a blueprint for other rail operators facing legacy network shutdowns. Many networks across Europe and beyond still depend on outdated mobile technologies that are being phased out. This project shows how combining rail‑specific systems with mainstream mobile platforms can maintain operational safety and performance while avoiding communication blackouts.

The successful rollout highlights strong collaboration between a national rail provider and a technology partner, bringing together engineering teams, multiple vendors and regulators. It also demonstrates that telecom modernisation can be achieved without disrupting daily rail services, even under tight industry deadlines.

What’s Next

Rail operators are thinking more and more about how to connect existing systems to new digital solutions. Switzerland’s track record shows us that for now, integrating old and new telecom technologies is better than waiting for FRMCS and other next-gen standards to be adopted. As technology progresses, future work will concentrate on full fleet migration and the introduction of new capabilities driven by advanced mobile networks.