Your message was flagged as objectionable and blocked by the receiving wireless carrier. Some carriers do this to enforce rules or regulations about what types of messaging are allowed to that country or mobile network. Many carriers also have systems in place to protect mobile subscribers from spam or unwanted messages.
Learn more about how carrier filtering works and how to avoid it: How Does Carrier Filtering Work?
For a detailed explanation of carrier filtering in the United States and Canada, please see SMS Carrier Filtering in the United States and Canada.