Disaster Inbound Roamer

Description

A Disaster Inbound Roamer is a user that (a) cannot get service from the PLMN it would normally be served by, due to failure of service during a Disaster Condition, and (b) is able to register with other PLMNs. This concept was introduced in 3GPP Release 17 as part of the disaster roaming framework. It allows users from a failed network to access services via other networks that are operational, even without a roaming agreement. The definition has remained unchanged across Releases 17-20.

When a Disaster Condition is declared, the network of the affected area may be partially or fully non-functional. Users with subscriptions to that network will not be able to register. However, if other PLMNs in the area are operational, they can accept registrations from these users as Disaster Inbound Roamers. The core network elements, such as the AMF in 5G or MME in 4G, are enhanced to support this. The user's equipment will attempt to register with any available PLMN, and if the PLMN supports disaster roaming, it will accept the registration.

The authentication and authorization procedures are adapted to allow users from failed networks to register without prior roaming agreements. The home network's subscriber data may be inaccessible, so the visited network may use default or limited subscription profiles. The user may be allowed to make emergency calls, access public warning systems, and possibly use other services depending on operator policy. The 3GPP specifications 22.261, 23.401, and 23.501 define the requirements and procedures.

The Disaster Inbound Roamer concept is part of a broader effort to enhance network resilience and ensure communication during disasters. It leverages the flexibility of 5G and 4G networks to provide service continuity. The network must handle the additional load and ensure that regular users are not adversely affected. Prioritization mechanisms may be used to manage resources.

In summary, the Disaster Inbound Roamer is a key enabler for disaster relief communications, allowing users to stay connected when their home network fails.

Purpose & Motivation

The Disaster Inbound Roamer concept was created to solve the problem of communication isolation during disasters. Before its introduction, users whose home networks failed could not register with other networks due to roaming restrictions and lack of standardized procedures. This meant that even if other networks were operational, affected users could not make calls or access data services. The Disaster Inbound Roamer allows these users to connect to any available network, ensuring that emergency calls and critical communications can take place.

This concept is particularly important for public safety and disaster response. It enables governments and relief organizations to communicate with affected populations and coordinate efforts. It also allows individuals to contact loved ones and access information. The solution builds on existing roaming and authentication frameworks but adds specific procedures for disaster scenarios, such as allowing registration without a roaming agreement and using default subscription data.

The Disaster Inbound Roamer is a key part of 3GPP's disaster roaming feature, which aims to make networks more resilient and responsive in emergencies. It addresses the limitations of previous approaches that relied on bilateral roaming agreements, which may not be in place or may be insufficient during a widespread disaster.