GRX (GPRS Roaming Exchange)

A private IP backbone used by mobile operators to exchange GPRS, 3G, and early 4G roaming traffic. GRX carries GTP signalling and user-plane tunnels between visited and home PLMNs, isolated from the public internet for performance and security. It has been progressively superseded by IPX, which adds service-level guarantees and supports Diameter and 5G traffic. GRX has historically been a target for GTP-based attacks because operators often trusted incoming peers implicitly.

Categories: Radio Access NetworkSignalingRoaming and Interconnect

GRX in context

The radio access network is the layer where mobile devices attach to the operator's infrastructure. Attacks in this layer include IMSI catching, rogue base stations, downgrade attacks and jamming, and defenses hinge on mutual authentication, integrity-protected signaling and Open RAN supply-chain hygiene.

Signaling protocols carry the control-plane instructions that set up calls, register subscribers, hand over sessions and route SMS. SS7, Diameter, GTP-C and SIP are the four dominant families, and interconnect exposure of any of them is treated by GSMA FS.11 / FS.19 / FS.20 as a top-tier telecom risk.

To place GRX in the wider telecom-security picture, review IBCF, Inter-PLMN Security, PLMN, Interconnect Security Model, Roaming Security Architecture and SOAR.

Related terms

Equipment

GRX/IPX edge, DNS and ENUM

Articles in the P1 mobile network security guide

Related topic hubs

  • Roaming Security IPX/GRX interconnect risk, home-routed vs local-breakout, SEPP.
  • Signaling Firewall Unified SS7/Diameter/GTP/SMS signaling firewall framework.
  • GTP Security GTP-C/GTP-U threats across S5/S8, N3/N9 and GRX/IPX borders under GSMA FS.20.
  • Diameter Security 4G/LTE Diameter threats across IPX/roaming and DEA defenses.

More from the TelcoSec Glossary

Browse the full TelcoSec Glossary, the Ultimate Guide to Mobile Network Security, or the P1 Arsenal of telecom-security tools.