As a high-quality merchant, they have signed a telephone debit agreement with the bank. Customers can deduct money by reporting their card number. Ctrip's own reputation is quite high - in addition, this debit method is only available to some customers. Services such as purchasing air tickets, because the air tickets themselves are special commodities, the person making the reservation needs to provide their name and ID number, and it is not easy to fake them, and it is generally required to purchase air tickets for the cardholder himself or for multiple people including himself. This method has basically no loopholes that can be exploited.