When war or natural disaster causes havoc around the world and millions of people are displaced or rendered homeless, communications and power infrastructures are often damaged or non-existent. Yet people are desperate to let their loved ones know they’re safe and to find out what’s going on. “The first questions people always ask when they arrive at a refugee camp are ‘Where can I charge my phone?’ and ‘Is there wi-fi?’,” says John Warnes, innovation…