Missed calls let Indian firms keep in touch with customers
There are more than 900 million mobile phone users in India - but most of them are on a tight budget and so they do what they can to keep the costs down.
Companies have found a way they can encourage people to get in touch with them - without having to foot the bill for the call.
The potential customer rings and then hangs up. The company then returns the call, knowing the caller has expressed an interest.
As David Reid reports from Delhi some surprising sectors are now developing strategies using missed calls.