FRMCS: The Future Railway Mobile Communication System
What is FRMCS?
The railway industry is entering a new era with the Future Railway Mobile Communication System (FRMCS), a standard designed to replace the aging GSM-R system and enable the digital transformation of railways worldwide.
At Westermo, we are proud to be part of this journey, working alongside industry organizations, operators, and technology partners to create open, future-proof solutions for mission-critical rail networks. Through ETSI and UNIFE, Westermo is taking an active role in standardization of FRMCS.
Transition from GSM-R to FRMCS
FRMCS (Future Railway Mobile Communication System) is the designated successor to GSM-R, the 2G-based system currently used for railway communications across Europe. GSM-R is being phased out due to its limited capacity, outdated architecture and availability of components, and inability to support modern digital services. FRMCS, by contrast, is built on open standards, including 5G, and is designed to support a wide range of services including signaling, voice, video, diagnostics, and passenger connectivity.
FRMCS vs GSM-R
GSM-R is based on 2G; FRMCS is based on 5G (3GPP Release 18), with support for railway-specific bands (n100/n101) and opens the door for broader wireless technologies like Wi-Fi, mmWave, and satellite and future communication protocols.
GSM-R supports limited voice and data; FRMCS enables multi-service support including MCX (Mission Critical Communications), ETCS, ATO, CCTV, and Passenger Information Systems.
GSM-R relies on dedicated infrastructure; FRMCS supports hybrid models with roaming across private and public networks, allowing aggregation of multiple wireless technologies.
FRMCS is designed to evolve with future 3GPP releases and supports modular onboard systems through interfaces like OBRAD, enabling long-term adaptability.
Westermo’s Role in Enabling FRMCS
At Westermo, we are committed to standardised, interoperable interfaces that align with UIC’s vision of FRMCS. Interoperability is essential to ensuring vendor independence, promoting innovation and enabling a resilient multi‑supplier ecosystem. To support this, the UIC is standardising the interfaces between the key components of the FRMCS system. One of the most critical is:
OBRAD - On‑Board Radio Interface.
OBRAD defines the interface between the onboard Communication Gateway and Radio Function. By separating gateway functions from the underlying radio technology, OBRAD supports a modular FRMCS architecture in which components from different suppliers can interoperate. This can reduce dependency on vertically integrated solutions and make it easier to evolve onboard communication systems as technologies and requirements change.
Westermo actively follows and supports this standardisation work, combining railway-grade communication platforms with expertise in secure wireless railway communications to develop solutions for future FRMCS architectures.
Current technical specification: ETSI TR 104 006 V1.1.1 (2025‑01)
Formalisation underway: ETSI TS 104 127 V0.0.1 (2025‑04)
FRMCS Deployment Timeline
Key Milestones Toward Full Adoption
The rollout of FRMCS is a multi-phase process coordinated by European rail authorities, industry groups, and technology vendors. The deployment of FRMCS is structured around a phased transition, ensuring continuity of operations while enabling modernization.
Why Westermo?
Your Partner for Mission-Critical Networks
Westermo has decades of experience in secure, reliable networking for the rail industry. As the sector transitions to FRMCS, we bring this experience into the development of railway-grade communication platforms designed for open, interoperable and modular architectures.
Our expertise spans rugged industrial networking, secure wireless railway communications and Radio Function technology, combined with active engagement in FRMCS and OBRAD standardisation. We work closely with operators, infrastructure managers, train builders and system integrators to support the transition from today's railway communication systems to the next generation of onboard connectivity..
Daniel Samo
Head of Product Management DACH, FRMCS Expert
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