How does Apple's mobile phone filter SMS advertisements?

Apple Mobile Phone Blocking Advertising SMS Settings-Mobile Phone-Blacklist-Edit (New)

1. First, find the Phone icon on the iPhone home screen, and then click Open.

2. Take the phone number in recent calls as an example, click the "Recent Calls" option at the bottom of the screen, and then click the phone number you want to add to the list. ...

3. In the phone number profile, slide your finger up on the screen, find the "Block this incoming number" option at the bottom, and then click Add.

4. Then the system will prompt us to block the phone, information and FaceTime of this number, and click "Block Contact". ...

5. If you want to unblock, click the "Unblock this calling number" option at the bottom of the contact details.