Is the telecom user to participate in the telecom company's contract purchase activities, each month the user promises a minimum consumption of 199 yuan, each month the telecom company returned to the user 80 yuan phone charges, equivalent to the user actually need to pay 119 costs per month. This is the telecom company in order to bind the user, to the user to promote the contract purchase activities, the user promised to guarantee the minimum consumption, the telecom company to give a certain phone subsidies