NTT DoCoMo has launched a new handset for old people, the RakuRaku Phone. Apparently "Rakuraku" means "comfortable" or "easy".

As well as increased speaker volumes, the phone has a GPS function that lets the user's family know where they are at the press of a button.

So this feature would let you go and find Gramps if he'd wandered off and gotten lost - as long as he can remember which button it was.