PLMN stands for Public Land Mobile Network, which is a wireless communication system that provides mobile services to the public. A PLMN consists of several cellular technologies, such as GSM, UMTS, LTE, and NR, offered by a single operator within a given country. A PLMN is identified by a unique PLMN code, which is composed of a Mobile Country Code (MCC) and a Mobile Network Code (MNC). For example, the PLMN code for AT&T in the USA is 310-410.
A PLMN typically offers the following services to a mobile subscriber:
• Emergency calls to local fire, ambulance, and police stations.
• Voice calls to and from any other PLMN or PSTN (landline or VoIP).
• Short Messaging Service (SMS) and Multimedia Messaging Service (MMS) to and from any other PLMN or SIP service.
• Unstructured Supplementary Service Data (USSD) for operator-specific interactions, such as checking the balance or activating a service.
• Internet data connectivity for various applications, such as web browsing, email, streaming, and social media.
A PLMN is an essential part of the mobile communication system, as it enables the users to access the network and enjoy the services. A PLMN also interacts with other networks and systems, such as the core network, the roaming network, the billing system, and the authentication system, to ensure the proper operation and performance of the network.