14 Simple Lessons and Tips That Could Save Your Life One Day
Emergency number
A useful thing to know is that most cell phones can dial a local emergency number, even when there is no SIM card. Even if you are in an area with no service at all, do not switch your phone off. An attempt to dial an emergency number could transmit an electronic lifeline that lets rescuers know you’re alive. This concept is called a "digital handshake."
