SMS Opt-Out Compliance: STOP, HELP and Quiet Hours

Getting subscribers is regulated; losing them is regulated harder. Opt-out handling is the compliance area where programs fail after launch, because mishandled STOPs generate carrier complaints, filtering, TCPA exposure, and campaign suspensions. The good news: the rules are mechanical. Implement them once, correctly.

STOP: the universal off switch

• Honor the standard keywords: STOP, plus the conventional set (STOPALL, UNSUBSCRIBE, CANCEL, END, QUIT). Case-insensitive, tolerant of surrounding whitespace.
• Effect must be immediate: the subscriber receives no further program messages after the STOP. "Processed within 24–48 hours" batch jobs are a violation pattern; process in real time.
• One confirmation message is permitted (and good practice): confirm the opt-out, name the program, and send nothing further. E.g. "Trailhead Outfitters: You’ve been unsubscribed and will receive no more messages. Reply START to resubscribe."
• Scope it correctly: STOP applies at least to the program/number it was sent to. If you run multiple campaigns, do not let a STOP on your marketing line silently continue on another marketing line; consumers (and courts) see one brand.
• Never require more steps. "To unsubscribe, visit our website and log in" fails; the reply itself must suffice.

Providers help: Twilio’s Advanced Opt-Out and default handling intercept STOP at the platform level and maintain suppression lists per number. Use it, but mirror the state into your own database, because your CRM must also know who is opted out.

HELP: the mandatory info desk

A HELP reply must return useful program information: who you are, and how to get support. E.g. "Trailhead Outfitters SMS: For help visit trailheadoutfitters.com/sms or email support@trailheadoutfitters.com. Msg & data rates may apply. Reply STOP to cancel." HELP responses are expected even for opted-out numbers.

Quiet hours

The established safe window for non-urgent messages is 8 AM to 9 PM in the recipient’s local time. Notes that matter in practice:

• Recipient’s local time, which you often don’t know precisely. Area code is an approximation (increasingly wrong with number portability); when uncertain, schedule inside a window that is safe for all US time zones (roughly 11 AM–8 PM ET).
• Some states are stricter; Florida’s telemarketing law, for example, uses 8 AM–8 PM and adds per-day contact limits for solicitation. If you send marketing nationally, adopt the strictest common denominator.
• Transactional urgency is different. OTPs and fraud alerts the user just triggered are fine at 2 AM; promotional blasts are not.

START and re-subscription

Support START (and YES/UNSTOP) to reverse an opt-out, but only resume sending after an actual START from the subscriber. Emailing "text START to rejoin!" to someone who texted STOP hours earlier is aggressive; give real space, and never re-add opted-out numbers through list imports.

The operational checklist

1. Platform-level STOP/HELP handling enabled and tested (text your own number).
2. Suppression list synced to your CRM/application within seconds, not days.
3. STOP semantics span all numbers that represent the same program.
4. Quiet-hour scheduling enforced in your sending code, not in a policy document.
5. Opt-out rate monitored per send. A spike is your earliest warning of content or consent problems, well before carriers act on it.

Frequently asked questions

Does a STOP confirmation message violate the opt-out?

No. One final confirmation of the opt-out is expressly permitted by CTIA guidelines and expected by consumers. It must confirm the unsubscribe and contain no promotional content. Anything after it is a violation.

What if someone replies "please stop texting me" instead of STOP?

Honor it. The FCC has made clear that consumers may revoke consent through any reasonable means, not just magic keywords. Modern practice (and Twilio tooling) recognizes natural-language revocations; when in doubt, suppress.

Do quiet hours apply to appointment reminders?

Reminders are informational, but sending them at 6 AM still generates complaints. Best practice: schedule all non-urgent traffic inside the 8 AM–9 PM window regardless of message type; reserve off-hours only for messages the recipient just requested (OTPs, fraud alerts).