Latest idea from the government, that's been ten years in the making, your mobile phone will bleep a warning and tell you your about to die.
Seriously though, the mobile phone service available in the U.K. a good % of the country has rubbish mobile phone network signals that don't reach certain parts {as yet} so once again putting the cart before the horse.
Yet another sidetracking idea detracting you from looking what's really going on.