The devices are split into active and passive systems. Active systems need the user to push a button or otherwise trigger the alarm manually. Passive systems make use of algorithms which can detect lack of activity, falls and so forth. Active devices need the user to be able to consciously activate the system to call for help. Passive systems are able to trigger the alarm based on their programming. These systems can include other accessories such as temperature changes, CO2 detection, flood detectors and more.