How to stop spam sms.

1. Block the sender

  1. First, within iMessage there will be a list of people, click on the name Of the person who wants to block.
  2. Next, tap on the tab named “Information”
  3. Then tap on the arrow sign.
  4. Last select Block This Number.

2. Turn on the iOS scanning system, whether the user is spam or not?

  1. Go to setting select Message and select “Filter Unknow Sender”

Just then, you will never see spam messages again.

Ref.wikipedia