Signalling With Missed Phone Call

WSJ: "5 Things You Can Get in India With a Missed Call".  From the article:

Want to transfer funds from your account? Give your bank a missed call. Want to hear Bollywood music? Dial a number and hang up.

Making a missed call by calling a number and letting it ring is a popular way of communicating in India because the caller doesn’t have to spend money. Marketing companies, politicians, banks and others now use this practice to reach millions who have cellphones but limited means.

Here are five things you can do in India by ringing a number and hanging up...