I got to know about this from a thread at DigitalPoint. It’s like when you search for something, you see an ad with green phone icon, you click on it, it asks you to enter your phone number and that’s it. You get a call from the advertiser within few minutes.
Very smart and different way of advertising.
Checkout the ads here (Currently it is on 2nd position, Makemytrip.com is the site)