How does China Unicom collect traffic by SMS?

At present, there is no SMS recharge service, but there is a way to open a traffic package through SMS, such as 100 yuan, half a year 1G national traffic package, and a *** 1G traffic. If the current month's traffic is not used up, it can be carried forward to next month. The half-year traffic package is valid for 6 months, excluding the month of ordering. If the flow in 1G is still not used up after 6 months, it will not be carried forward. Send "5082" to 100 10 to apply for opening.