Inter-PLMN Security

Inter-PLMN security covers the controls applied to signalling and user-plane traffic exchanged between two mobile operators, typically over GRX/IPX. It includes Diameter and SS7 firewalling, GTP firewalling on the user plane, mutual TLS plus IPsec at the transport layer, and in 5G the SEPP enforcing PRINS application-layer protection on the N32 interface. The objective is to prevent a malicious or compromised partner from tracking subscribers, intercepting traffic, or committing interconnect fraud.

Categories: Radio Access NetworkSignalingRoaming and Interconnect

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

Related terms

Related topic hubs

  • Signaling Firewall Unified SS7/Diameter/GTP/SMS signaling firewall framework.
  • Roaming Security IPX/GRX interconnect risk, home-routed vs local-breakout, SEPP.
  • SEPP Security N32-c/N32-f, PRINS, JWE and OAuth 2.0 at the 5G roaming edge.
  • 5G Security 5G SBA, SEPP, SUCI, 5G-AKA, N32 and service-based interface security.

More from the TelcoSec Glossary

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