What is the term for communication systems that provide continuity when primary methods fail?

The term "redundant" refers to communication systems that are designed to ensure reliability and provide continuity in case primary communication methods fail. In the context of emergency management and disaster response, redundancy is crucial as it enhances resilience by having backup systems that can activate when the main systems are compromised. This redundancy can include multiple forms of communication such as satellite phones, two-way radios, and internet-based systems, all of which are kept in place to ensure seamless communication during crises when primary systems may not function due to power outages or infrastructure damage.

Other terms like "alternative" and "secondary" suggest different types of backup systems but do not inherently imply that they are meant to replace or support primary systems in a reliable manner during failures. "Fallback" often describes a response or strategy that is employed after a primary method has failed, rather than a system that is set up alongside it to ensure continuity.