How does China Unicom set up a blacklist?

If you mean that this number always receives spam, you can stop it in the following ways:

1. The number starts with 106: you can record the number through local manual customer service and block it;

2. The number is the mobile phone number: you can send "LJDXB # number # content" to 100 10, free of SMS information fee. Android mobile phone users can log in to the Android version of the mobile phone business hall client, click customer service > spam report, and enter the spam report page to report spam messages.

3. There is no number, but there is a link URL: you can turn off the service/push information through your mobile phone. I suggest you pay attention to it.