SMS is the most intimate channel a brand can use. It sits beside messages from family. Used well, for moments that matter, it’s the highest-intent channel you have. Used as a second email list, it’s intrusive, expensive per message, and a legal exposure.

This chapter is an operator’s summary of the rules as of September 2026, not legal advice. The rules differ by state and change often. Have counsel review your consent language and sending rules before you scale.

Consent comes first

Under the US Telephone Consumer Protection Act, marketing texts sent with an autodialer require the recipient’s prior express written consent Published. In 2021 the Supreme Court, in Facebook v. Duguid, narrowed what counts as an autodialer, and some argued that removed most SMS platforms from the rule. Don’t build on that argument. Several states have their own versions of the law, carriers have their own rules, and written opt-in remains the industry standard. Collect it clearly: what they’ll receive, roughly how often, that message and data rates may apply, and how to stop.

When you can send

• Federal quiet hours: no telephone solicitations before 8 a.m. or after 9 p.m. in the recipient’s local time Published.
• Florida is stricter: no commercial solicitation calls or texts before 8 a.m. or after 8 p.m., and no more than three on the same subject in 24 hours Published. Other states have their own rules.
• In practice: send in the recipient’s time zone, inside the narrowest window that applies to any state you sell into.

The carriers’ rules

US carriers require businesses texting from ordinary ten-digit numbers to register their brand each messaging campaign through The Campaign Registry, a system known as A2P 10DLC. Unregistered traffic is blocked; Twilio has blocked it since September 2023 Reported. Your SMS platform handles most of this. Make sure it’s done, and that what you register matches what you actually send.

Stopping has to be easy

Honor STOP and its common variations immediately, and confirm the opt-out with one final message. If you sell subscriptions, cancellation belongs in the same spirit. The FTC’s “click to cancel” rule was adopted in October 2024 and vacated by a federal appeals court in July 2025. In March 2026 the FTC started the rulemaking again Published. It still enforces existing law against subscriptions that are hard to cancel, and several states have their own auto-renewal rules. Make cancelling as easy as signing up, whatever the federal rule says this year.

Every SMS you send should be one the customer would be glad to get. The law just makes that expensive to forget.

Growing the SMS list

The best SMS sign-ups come from people who already gave you their email, on the second step of the form described in chapter 12, with their own reason to say yes: early access, restock alerts, or a small extra on the first order. Keyword sign-ups on packaging and at events work too. Don’t buy lists, don’t import phone numbers collected for order updates into marketing, and don’t pre-check a consent box. Each of those is a fast way to a complaint.

What SMS is for

• High-intent moments: cart recovery, a restock of something they wanted, shipping updates, the last hours of a sale they were told about.
• Launches for people who asked: early access for your top customers.
• Coordinated with email, not copied from it. If both channels fire the same message at the same moment, one of them is wasted. Let SMS carry the urgent step and email the detail.
• Short, human and signed. Straight apostrophes, no walls of emoji, one link.

Do this

• Pull your SMS consent language, your quiet-hours setting and your 10DLC registration status, and send all three to counsel. Then cut SMS campaign frequency to the sends you’d be glad to receive yourself.