Definition: STOP and HELP keywords are standard text replies that let a consumer opt out of an SMS program (STOP) or get program and support information (HELP).

These keywords give people control. Anyone who gets your texts should be able to leave at any time or ask who you are. Carriers check that your campaign handles both.

What are the keyword rules?

TCR lists subscriber opt-out as mandatory for every campaign except 2FA and Machine to Machine.

Where should STOP and HELP appear?

• In your opt-in call-to-action next to the checkbox.
• In your SMS terms on your website.
• In your first opt-in confirmation text.
• In at least one sample message, as Twilio error 30893 suggests for opt-out language.

Your HELP reply should name your brand and give a phone number or email. Your STOP reply should name your brand and confirm no more texts will be sent.

Included in your Registration Kit: your opt-in confirmation, HELP reply and STOP reply, written with your brand name and support contact, ready to paste into your provider's form. Build my order →

Why it matters for your website

Providers like Telnyx, Vonage, and Plivo ask for STOP and HELP instructions in your call-to-action and your SMS terms page. If those pages skip them, reviewers can flag your campaign. See SMS terms requirements.

Related terms: Opt-in, A2P, Campaign use case

Sources

• CTIA Messaging Principles and Best Practices (May 2023)
• The Campaign Registry: CSP User Guide (October 2025)
• 47 CFR 64.1200 (Cornell LII)
• Twilio Error 30890: Subscriber help
• Bandwidth: 10DLC campaign vetting tips and tricks
• Twilio Error 30893: Sample messages
• Telnyx: 10DLC Campaign Compliance Guide
• Vonage: 10DLC Campaign requirements
• Plivo: A2P 10DLC registration guidelines

Our SMS terms pages include STOP and HELP language by default. See pricing, or check your site at compare your site with the checklist.