How did Unicom's number get blacklisted?

Unicom numbers are blacklisted as follows:

1. Arrears for three months of downtime include cancelled users and non-cancelled users.

2. Malicious arrears users, such as users who maliciously defraud international information stations and users who maliciously defraud international roaming charges.

3. Users suspected of short message fraud, fraud and other criminal acts identified by public security organs.