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Wireless industry standards for protecting consumers and maintaining message deliverability.

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What is CTIA?

CTIA (the wireless industry association) established messaging principles that go beyond legal requirements to protect consumers from spam and unwanted messages. Mobile carriers use these principles to filter and block messages that don’t follow best practices.
Why this matters: Even if your messages are legally compliant, carriers may filter them if you don’t follow CTIA guidelines. Following these principles ensures your messages reach recipients and maintains your sender reputation.

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Three core principles

Get consumer permission before sending messages, even when not legally required. Consumers should actively choose to receive your messages. Valid consent methods include:
  • Website form with checkbox (not pre-checked)
  • Mobile webpage button click
  • Keyword opt-in (e.g., “Text JOIN to 12345”)
  • In-person sign-up at events
  • QR code scan with explicit opt-in
  • Phone opt-in via IVR (interactive voice response)
When collecting consent, provide clear disclosures (called “call-to-action”) about what consumers are signing up for. Required disclosures include:
  • Program description: What types of messages will they receive?
  • Sender identity: Who is sending the messages (campaign name)?
  • Message frequency: How often will they receive messages?
  • Opt-out instructions: How to stop messages (Reply STOP)
  • Terms & Privacy: Link to terms of service and privacy policy

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3. Honor opt-out requests

Consumers must be able to opt out at any time, and you must honor requests immediately. Opt-out requirements:
  • Support STOP keywords: STOP, UNSUBSCRIBE, CANCEL, QUIT, END
  • Multiple methods: Reply to text, phone call, email, web form
  • Immediate processing: Remove from lists within seconds (automated)
  • No re-subscription: Stay opted out unless they explicitly opt back in
  • Confirmation message: Send one final message confirming opt-out

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What NOT to do (spam triggers)

Don’t share phone lists. Consent to one organization doesn’t transfer to another. No selling, leasing, or sharing recipient lists without explicit permission.Don’t pre-check opt-in boxes. Consumers must actively choose to opt in. Pre-checked boxes or hidden opt-ins don’t count as consent.Don’t bury disclosures. Call-to-action must be clear and conspicuous, not hidden in fine print or long terms of service.Don’t use deceptive language. Be honest about who you are and why you’re texting. No misleading subject lines or sender names.Don’t ignore opt-outs. Continuing to text after STOP is received is illegal and damages your reputation with carriers.

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How carriers filter spam

Mobile carriers and messaging service providers use spam filters to protect consumers. Messages get flagged if they:
  • Generate high complaint rates (users marking as spam)
  • Have high opt-out rates or ignored STOP requests
  • Come from unregistered or suspicious phone numbers
  • Contain spam-like content (excessive links, ALL CAPS, deceptive language)
  • Send during restricted hours (before 8 AM or after 10 PM)
  • Show patterns of automated dialing without human interaction
Following CTIA guidelines prevents filtering and ensures your messages are delivered consistently.

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Official resources