South Carolina and the United States have laws that regulate text messaging, including opt-in requirements for businesses: 

• Opt-in requirements
  Businesses must obtain written consent, or an opt-in, before sending text messages to customers. This includes businesses that already have a customer’s phone number. 

Cold texting is illegal. It is also illegal to send a text message asking a customer to opt-in to a text program. 

• Misleading text messages
  It is illegal to send text messages with the intent to defraud, harass, cause harm, or wrongfully obtain anything of value. 
• Penalties
  Businesses that violate the Telephone Consumer Protection Act (TCPA) can be fined up to $1,500 per text message or phone call. 
• Opt-out requirements
  Businesses must provide an easy way for customers to opt-out of receiving text messages. 
• Disclosure requirements
  Businesses must include a comprehensive opt-in message that discloses the business name, purpose of the message, data rate notices, and frequency of texts. 
• Do Not Call Registry
  Businesses should respect the Federal Trade Commission (FTC) National Do Not Call Registry and honor opt-outs. 
• State Do Not Call Lists
  Businesses should observe applicable state Do Not Calls lists that reference text marketing.