The new software is included in iOS 13.7 for iPhones (and the iOS 14 update this coming fall), and Google will follow later this month with their Android software update. When users update their phones, the feature is disabled by default.
When states opt into the system, most iPhone and Android phones in that state will get an invitational push notification inviting the owner to take part in the system.
Opting in will activate the new ENE feature, and the system uses anonymous digital tokens or randomly generated ID numbers to exchange data with other phones via short-range Bluetooth. Personal identity and location data are neither collected nor sent to states.
If one user self-reports that they test positive for COVID-19, the system notifies other participating phones that have been in the vicinity and may have been exposed to the virus.