Primarily in the United States, but also abroad, carriers filter SMS and MMS messages using a variety of methods, including:

  • Keyword filtering: Carriers block messages that contain certain keywords.
  • Content filtering: Carriers block messages that contain prohibited content using machine learning.
  • Number filtering: Carriers block messages from blacklisted numbers (e.g., those consistently reported as spam).

Local carriers ultimately have the authority to determine what kind of traffic flows over their networks. This means that the carriers might impose restrictions on SMS / MMS that exceed the minimum requirements of the law.

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Prohibited Topics

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Prohibited Keywords

This is not an exhaustive list.