Receive Phone Calls get Money

If we see since the beginning of the year, signs of price war (a war tariff) to start the service, and the peak at this time. Almost all operators offering the cheapest rates.

Even if you see, Esia and Three, to give the gimmick / promotion form to receive a phone call gets the money. Three provide Rp. 100; per minute when customers receive a call from another operator for a minute. Is this promo does not harm the operator?

The answer "no". Because the Regulator (the government) has set the interconnection charges for voice calls (voice). So when a customer service call to customer B, the operator must pay a cost of interconnection to the customer B. So the cost of this is played by the operator to give a bonus to customers when receiving a phone call.