I used SF City Knight software to call out all the people in Shenzhen, Guangdong. Why?

The reason for calling out with SF City Knight software is to prevent privacy leakage, and they are all virtual numbers. According to the relevant information of the inquiry, the mobile phone numbers dialed by the courier brother are all dialed by the company in a specific way. Calling the customer, the displayed mobile phone numbers are all virtual numbers, and the mobile phone numbers in SF City are all virtual numbers. The same city is in the same city, the same city.