If you observe, at this time the price of starterpack card or mobile very cheap to average around Rp. 5000 while still at the top of the previous Rp. 10000. With the price of five thousand is a balance of Rp. 10000.
Try to compare it with your free voucher to buy 10,000 denominations; the price of Rp. 10000. Far cheaper to buy starterpack.
But yes its a risk we always change the number. But for some people to change the number is not a problem, can be an important call with cheaper rates.
For operators, this course is very detrimental. Cost of making the card the price of around Rp. 4000 per card. Should give more credits. In addition there will be a number of customer churn. Plans screaming customers out of the reach at this time, the growth. But it's only temporary, we see the future there will be a massive churn.