PLMN ID (Public Land Mobile Network Identifier)

Also known as: Public Land Mobile Network Identifier, PLMN Identifier

A PLMN ID is the globally unique identifier of a mobile network operator, formed from a Mobile Country Code (MCC) and Mobile Network Code (MNC). It is broadcast by every cell, embedded in IMSI/SUPI, GUTI and slice identifiers, and used throughout SS7, Diameter and 5G SBI signalling to name the home and visited networks in every roaming exchange.

Categories: Radio Access NetworkRoaming and InterconnectIdentity and Subscriber

PLMN ID 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.

Roaming and interconnect are where two operators exchange signaling and user-plane traffic. Trust boundaries here are the primary attack surface for location tracking, SMS interception and fraud, which is why GSMA now mandates SEPP with PRINS on 5G interconnect.

To place PLMN ID in the wider telecom-security picture, review AKA, iSIM, MNC, SUPI, vSIM and SUPI Concealment — each entry cross-references back to this page so you can walk the topic in either direction.

Related terms

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.