This specific scenario has not been addressed by the Federal Communications Commission (FCC). In these sorts of circumstances, the FCC looks at a number of factors to determine who is responsible for user-initiated messages such as: Who decides when the text is going to be sent? Is it being used to do an unlawful activity? Are you spoofing? The issue is control. In this case, the fact that the consumers are going to be the ones sending the message and are choosing who receives the message makes it seem like the consumer should be responsible. But they are promoting your product, so there could be a vicarious liability issue.