---
title: "Understanding PLMN: Public Land Mobile Network"
description: "Learn about PLMN identifiers and their importance in mobile telecommunications."
updated: "2023-08-22"
canonical: "https://mcc-mnc.org/wiki/understanding-plmn"
---

# Understanding PLMN: Public Land Mobile Network

## Understanding PLMN: Public Land Mobile Network

A Public Land Mobile Network (PLMN) is the complete infrastructure operated by a single mobile network operator to provide terrestrial mobile telecommunications services. More commonly, the term PLMN is used to refer to the unique identifier assigned to each mobile network operator's network.

### PLMN Identifier Structure

The PLMN identifier is a combination of two components:

```
PLMN = MCC + MNC
```

Where:
- **MCC (Mobile Country Code)**: A three-digit code identifying the country
- **MNC (Mobile Network Code)**: A two or three-digit code identifying the specific network operator

For example, the PLMN identifier 310410 breaks down as:
- 310: MCC for the United States
- 410: MNC for AT&T

### PLMN in Network Operations

PLMNs serve several critical functions in mobile telecommunications:

#### 1. Network Identification and Selection

- Mobile devices use PLMN identifiers to distinguish between different networks
- The device compares available PLMNs against its preferred PLMN list stored on the SIM
- This determines which network the device attempts to connect to first

#### 2. Roaming Management

- When a subscriber roams internationally, the visited network identifies the home network using the PLMN
- Roaming agreements between operators are established based on PLMN identifiers
- Authentication and billing information is exchanged between networks using PLMNs as reference

#### 3. Interconnection

- PLMNs identify networks for interconnection purposes
- Call routing between different mobile networks relies on PLMN identification
- Inter-operator billing and settlements use PLMNs for accounting

### PLMN Broadcasting and Discovery

Mobile networks broadcast their PLMN identifiers to enable device connection:

#### Cell Broadcast Information

- Base stations continuously broadcast their PLMN identifier
- This allows mobile devices to identify which networks are available
- Signal strength measurements are associated with specific PLMNs

#### Network Scanning

- When a mobile device performs a network scan, it detects available PLMNs
- The device displays these as available networks to the user
- In automatic mode, the device selects the appropriate PLMN based on preferences

### PLMN in Different Network Technologies

The use of PLMN identifiers has evolved across generations of mobile technology:

#### 2G (GSM) Networks

- PLMNs were first standardized with GSM technology
- Simple PLMN-based network selection
- Limited to voice and basic data services

#### 3G and 4G Networks

- Enhanced PLMN selection algorithms
- Support for multiple radio access technologies under the same PLMN
- More sophisticated preferred PLMN lists with technology preferences

#### 5G Networks

- Continued use of PLMN identifiers for network identification
- Support for network slicing within a single PLMN
- Enhanced security for PLMN selection to prevent spoofing

### PLMN in Network Sharing Scenarios

As operators increasingly share infrastructure, PLMN handling has become more complex:

#### Multi-Operator Core Networks (MOCN)

- Multiple operators share radio access network (RAN) infrastructure
- Each operator maintains its own distinct PLMN
- The shared RAN broadcasts multiple PLMN identifiers

#### Multi-Operator Radio Access Network (MORAN)

- Operators share physical infrastructure but maintain separate radio carriers
- Each carrier broadcasts its own PLMN
- Devices connect to the appropriate carrier based on PLMN

#### National Roaming

- One operator's subscribers use another operator's network in specific regions
- The device connects to a different PLMN than its home PLMN
- Special configurations enable this domestic roaming capability

### Regulatory Aspects of PLMNs

PLMNs are subject to regulatory oversight:

- National regulatory authorities assign MNCs within their country
- Regulations may govern PLMN selection to ensure fair competition
- Emergency call handling may override normal PLMN selection rules
- Some countries require registration of all PLMNs operating within their territory

### PLMN in Consumer Experience

From a user perspective, PLMNs typically appear as:

- Network names displayed on the device (e.g., "AT&T", "Vodafone")
- These display names are mapped to PLMNs in the device's software
- When selecting networks manually, users choose from a list of available PLMNs
- Network signal indicators show connection status to the current PLMN

## Related articles

- [What is a Mobile Country Code (MCC)?](https://mcc-mnc.org/wiki/what-is-mobile-country-code.md)
- [What is a Mobile Network Code (MNC)?](https://mcc-mnc.org/wiki/what-is-mobile-network-code.md)

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