In India, friends intentionally call each other, let it ring once or twice, and hang up. That's their way of sending a signal, like "I'm home safe," without being charged for a call in a country with pricey telecommunications and limited Internet accessibility. California native Valerie Wagoner moved to Bangalore, noticed the missed calls, and is now responsible for 416 million of them: That's how many times people have used her company, ZipDial, to connect with brands including Gillette, Disney, Procter & Gamble, and IndiaInfoLine.
It works like this: