PLMN (Public Land Mobile Network)

A Public Land Mobile Network is a regulator-licensed mobile network identified globally by the combination of its Mobile Country Code and Mobile Network Code (the PLMN-ID, e.g. 208-10 for a French operator). The PLMN-ID is broadcast on every cell, included in the IMSI/SUPI, and used in inter-operator signalling to identify the home and visited operator. In 5G, PLMN-IDs feed into SEPP routing and PRINS protection of N32 messages between networks.

Categories: Radio Access NetworkSignalingRoaming and Interconnect

PLMN in context

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

Signaling protocols carry the control-plane messages that set up calls, register subscribers 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 as top-tier telecom risk.

To place PLMN in the wider telecom-security picture, review PSTN, Firewall, Interconnect Security Model, Inter-PLMN Security, Telecom Attack Surface Mapping and GRX: each entry cross-references back to this page so you can walk the topic in either direction.

Related terms

Related topic hubs

  • 5G Security 5G SBA, SEPP, SUCI, 5G-AKA, N32 and service-based interface security.
  • 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 Penetration Testing Pentesting the 5G core, SBA, SEPP, and gNB interfaces.

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.