Disaster roaming is the ability for a mobile device to connect to another carrier’s network during an emergency when its home network is unavailable, overloaded, or intentionally constrained. It is a continuity feature, not a security control, but it can be critical when normal communications break down.
In cyber security and resilience planning, disaster roaming matters because attacks, outages, natural disasters, and large-scale congestion can all prevent users from reaching their usual provider. With roaming fallback, essential staff may still send alerts, coordinate response, and access time-sensitive services. Defenders test this behavior in drills to see whether devices, SIM profiles, and carrier agreements actually allow recovery under pressure. If roaming is misconfigured, disabled, or unsupported, emergency communications can fail even when another network is nearby.