GSM-R
GSM-R (GSM-Railway) is a rail-specific variant of the GSM mobile standard that provides voice and data communication between trains and trackside, and carries ETCS Level 2 and 3 movement authorities. It is being succeeded by FRMCS, the 5G-based Future Railway Mobile Communication System.
How it works
GSM-R operates in dedicated frequency bands reserved for railways and adds rail-specific features to GSM: functional addressing (calling a train by its number), location-dependent addressing (reaching the controller responsible for the train's current position), railway emergency calls and group calls. For ETCS, it provides the circuit-switched or GPRS data bearer between the onboard unit and the Radio Block Centre.
FRMCS, based on 5G and IP, is designed to replace GSM-R over the coming decade while supporting the same safety-critical applications plus new data-intensive ones.
Why it matters for security
GSM-R is a 2G-era technology carrying safety-critical ETCS data, and its cryptographic protections are limited by today's standards. The migration to FRMCS introduces IP-based, software-defined radio networks into signaling, bringing both stronger security mechanisms and a broader attack surface that must be monitored.
Related solution
Operating ERTMS across national rail networks
Protecting the radio path that carries safety-critical ETCS authorities.
See the solution →
