I was thinking more of in tactical or secure situations where phones are not permitted due to SIGINT & other security concerns.
What will the ID be for those occasions where you can’t carry electronic devices.
The only thing I can think of as I type this is some sort of sub dermal microchip like we do with cats & dogs that can then be read with a scanner.
IET - Personal Chips get under your skin
Think we may be a few years away though not to mention the ethics of microchipping children.