Wow these guys must have a huge phone bill, maybe turn the call back on them, when you answer say that you don't have a car but your from a call center in India and would like to offer them a new phone service and a free mobile and ask if you can phone them back etc, another trick is to receive their call and just put the phone receiver down on your desk so you cant hear it and let them go for it, when you know its finished just hangup. remember they are paying for the wasted time of the call.