suziewoozie
Alegrias I don’t have the technical language but my understanding is that this is all aboutBluetooth which is both hardware and software and the former is built into the phone and can’t be upgraded if the phone doesn’t have it already.
That's how I see it too suziewoozie
Here's the technical language from the government website
To install and use the NHS COVID-19 app, your phone will need Bluetooth Low Energy (BLE) 4 or above (that's the hardware bit) and Operating System software Android Marshmallow, or iOS 13.5 or above (this is the software bit). This is because the app needs the Exposure Notification framework developed by Apple and Google, which is only available in these versions.