SMS Marketing Best Practices: Which Ones Are Law, Carrier Policy or Judgment

Many SMS marketing best practices are rules, not tips. Written consent and honoring opt-out words come from the FCC’s TCPA rule, which also sets an 8 a.m. to 9 p.m. window for telephone solicitations; state laws such as Florida’s add more; CTIA’s carrier guidance covers disclosures and HELP. The judgment calls are frequency, timing and content.

An SMS best-practice checklist reads as one list, but its lines have three different authors and three different consequences. This guide separates them, quoting the federal rule, two state statutes and the carriers’ own guidance as served on October 8, 2026, then gives SMS marketing examples by shopping moment. It is published by Relvino, which decides per shopper across email, SMS and pop-ups, so read it as informed but interested. It is not legal advice.

Three rulebooks behind one checklist

Every common SMS best practice traces to one of three sources, and they differ in who wrote them and what happens when a brand ignores them:

• Federal law. The Telephone Consumer Protection Act and the FCC’s rule under it, 47 CFR 64.1200. Breaking it is a legal exposure.
• State law. A growing set of state statutes, often called mini-TCPAs, that add definitions, hours and remedies of their own. Florida and Oklahoma are the two quoted here.
• Carrier policy. CTIA’s Messaging Principles and Best Practices and the 10DLC registration system the carriers use. Its own scope section says the document does “not constitute or convey legal advice”; ignoring it is a deliverability problem rather than a lawsuit, since carriers can filter or block traffic.

Whatever none of the three requires is a judgment call, a smaller category than it first appears.

What the federal rule requires

Written consent for marketing texts

The FCC rule defines the consent an autodialed marketing text needs. Prior express written consent is “an agreement, in writing, bearing the signature of the person called that clearly authorizes the seller to deliver or cause to be delivered to the person called advertisements or telemarketing messages using an automatic telephone dialing system or an artificial or prerecorded voice,” plus the phone number it covers. The signature can be electronic, and the disclosure must tell the person they are “not required to sign the agreement (directly or indirectly), or agree to enter into such an agreement as a condition of purchasing any property, goods, or services.”

That clause is why signup forms say consent is not a condition of purchase: it is part of the legal definition.

Federal quiet hours: 8 a.m. to 9 p.m.

The rule says no person or entity shall initiate any telephone solicitation to a residential subscriber “before the hour of 8 a.m. or after 9 p.m. (local time at the called party’s location)”. Paragraph (e) extends that section to texts to wireless numbers, but telephone solicitation is defined to exclude a message to a person who gave “prior express invitation or permission”, so whether the window binds texts to a consented list is a question for counsel. The safe practice is to honor it on the recipient’s clock, which makes time zone a required field.

Seven opt-out words and ten business days

Honoring STOP is the familiar version. The current rule is broader. Replying with “stop,” “quit,” “end,” “revoke,” “opt out,” “cancel,” or “unsubscribe” to a text “constitutes a reasonable means per se to revoke consent”, and other wording counts too: the sender “must treat that reply text as a valid revocation request if a reasonable person would understand those words to have conveyed a request to revoke consent.” Revocations “must be honored within a reasonable time not to exceed ten business days from receipt”, and a sender “may not designate an exclusive means to request revocation of consent.”

The rule also allows exactly one reply: a confirmation that “merely confirms the text recipient’s revocation request and does not include any marketing or promotional information”. Sent within five minutes, it is presumed covered by the original consent. A “before you go, here is 15% off” reply to STOP is exactly what falls outside that allowance.

What state law adds, and where it sits

Florida’s telephone solicitation statute, section 501.059, names texts directly in its current text: a “telephonic sales call” means “a telephone call, text message, or voicemail transmission to a consumer for the purpose of soliciting a sale”. It requires prior express written consent for automated sales calls, counts “checking a box indicating consent or responding affirmatively to receiving text messages” as a signature, and gives the recipient “actual damages or $500, whichever is greater.”

The current text also writes the opt-out keyword into the law. Before suing over text solicitations, a recipient must reply “STOP,” and “Within 15 days after receipt of such notice, the telephone solicitor shall cease sending text message solicitations”.

The hours and the daily cap are not in section 501.059. They are in section 501.616, part of Florida’s Telemarketing Act, which says a “commercial telephone seller or salesperson” may not make “A commercial telephone solicitation phone call before 8 a.m. or after 8 p.m. local time in the called person’s time zone”, nor “More than three commercial telephone solicitation phone calls from any number to a person over a 24-hour period on the same subject matter or issue”. Its exemptions, in section 501.604, expressly do not reach subsection (6), so the hours and the cap survive them; what is open is that the subsection is worded for phone calls.

Oklahoma’s Telephone Solicitation Act of 2022 has the same split. Its consent definition covers a sales call “by telephone call, text message, or voicemail transmission”, while its hours and cap section, with the same 8 a.m. to 8 p.m. window and three per twenty-four hours on one subject, again speaks of “phone calls”. Unlike Florida’s, its exemptions cover the whole act, including soliciting people who “have previously purchased from the business enterprise”.

Whether those hours and caps reach a retailer’s marketing texts is exactly the question to put to counsel, and the safe operating answer is to treat the narrower window as binding for shoppers in those states. The consent rule and the timing rule sit in different sections, with different scopes and different enforcement paths.

What carriers expect: CTIA and 10DLC

Carrier policy is where the formatting rules in this guide come from. CTIA’s document asks that a signup call-to-action make shoppers aware of five things: the program, the sending number or short code, who is sending, the opt-in and any fees, and terms such as how to opt out, customer care and the privacy policy. It adds that “opt-in details should not be obscured in terms and conditions”.

It then asks for a confirmation text before anything else is sent, carrying the program name, a customer care contact or “HELP command instructions”, how to opt out, “a disclosure that the messages are recurring and the frequency of the messaging”, and the fee language. Three more lines carry real operational weight:

• Consent does not travel. “A Consumer opt-in to receive messages should not be transferable or assignable”, and senders “should not use opt-in lists that have been rented, sold, or shared”.
• Numbers expire. Senders “should process telephone deactivation files regularly (e.g., daily) and remove any deactivated telephone numbers”.
• Links must identify the brand. Where a link shortener is used, it should be one “dedicated to the exclusive use of the Message Sender”, which rules out public shorteners shared with everyone else.

10DLC is the registration layer for texts sent from ordinary ten-digit numbers. The Campaign Registry describes it as “an A2P messaging channel in which Brands and Campaign Service Providers (CSPs) are verified prior to being allowed to send messages”, and notes that “direct registration with TCR is not available for Brands”: the SMS platform registers the brand and each campaign on its behalf.

CTIA’s document sets no time-of-day rule and no numeric frequency cap; it asks for a disclosed frequency.

• Written consent before marketing texts, not a condition of purchase · Source: FCC rule, 47 CFR 64.1200(f)(9); Florida 501.059; Oklahoma 2022 Act · Kind: Law
• No texts before 8 a.m. or after 9 p.m., recipient’s local time · Source: FCC rule, 64.1200(c)(1) and (e) (telephone solicitations) · Kind: Law, scope for counsel
• Honor stop, quit, end, revoke, opt out, cancel, unsubscribe and plain-language requests within ten business days · Source: FCC rule, 64.1200(a)(10) · Kind: Law
• One opt-out confirmation, no promotion in it · Source: FCC rule, 64.1200(a)(12); CTIA 5.1.3 · Kind: Law and carrier policy
• 8 a.m. to 8 p.m. and three per 24 hours on one subject · Source: Florida 501.616; Oklahoma 775C.4 (worded for phone calls) · Kind: Law, scope for counsel
• Disclosures in the signup call-to-action, confirmation text, HELP · Source: CTIA 5.1.1 and 5.1.2.1 · Kind: Carrier policy
• Brand and campaign registration for ten-digit numbers · Source: 10DLC via The Campaign Registry · Kind: Carrier policy
• How often, which hour inside the window, what to say · Source: None of the above · Kind: Judgment

What is genuinely a judgment call

Strip out the rules and three decisions remain:

• Frequency below the cap. Outside the state sections above, nothing caps it, and CTIA asks only for a disclosed frequency. Whatever number the signup form promised is the ceiling the shopper agreed to; the right number below it differs by shopper, since a weekly buyer and a once-a-year gift buyer did not sign up for the same relationship.
• Timing inside the window. 8 a.m. to 9 p.m. is when a text is permitted, not when it is welcome. A cart reminder belongs near the session that created the cart; a launch announcement belongs when the shopper tends to buy.
• Content and channel. A text interrupts in a way email does not, so the test is whether this message is worth an interruption for this shopper today. The Klaviyo SMS marketing guide covers how one platform coordinates the two channels, and the Black Friday email marketing guide covers the week when both get crowded.

SMS marketing examples by moment

The messages below are illustrations written for this guide, not copied from any brand, and they make no performance claim. Each shows the elements the rules and CTIA call for. “Brand” stands for the sender’s name; CTIA asks that shoppers know who is represented in the initial message.

Signup and opt-in confirmation

Signup form disclosure, next to the phone field and an unchecked box: “By checking this box, I agree to receive recurring automated marketing texts from Brand at the number provided. Consent is not a condition of purchase. Up to 6 msgs/week. Msg & data rates may apply. Reply HELP for help, STOP to cancel. See Terms and Privacy.”

Confirmation text: “Brand: You’re in for recurring texts about new arrivals and offers, up to 6/week. Msg & data rates may apply. Reply HELP for help, STOP to cancel.” It covers CTIA’s five confirmation elements, and nothing is sent before it.

Cart recovery

“Brand: The linen shirt in your cart is still there, size M. Finish checkout: example.com/c/8k2 Reply STOP to opt out.” Short, tied to one session, with a link on the brand’s own domain. A discount is a separate decision for each shopper, not a default line.

Back in stock

A keyword reply such as “Text NOTIFY to the number below” is itself an opt-in mechanism CTIA lists, so the confirmation should say exactly what was agreed to: “Brand: We’ll text you once when the Field Jacket in olive is back. Reply STOP to cancel.” If the shopper agreed to one alert, recurring promotions need their own consent.

Shipping and delivery

“Brand: Order 10482 has shipped and should arrive Thursday. Track it: example.com/t/10482 Reply STOP to opt out.” A shipping update is informational, and the written-consent definition is tied to “advertisements or telemarketing messages”. Adding a promotion to it changes what kind of message it is, so keep the two separate or confirm with counsel that the shopper’s consent covers both.

The opt-out reply

“Brand: You’re unsubscribed and won’t receive more texts from us.” One message, within five minutes, with no offer, as the federal rule describes.

How to do SMS marketing, in order

1. Choose a platform and register. The platform registers the brand and campaigns for 10DLC or provisions a toll-free or short code number. The Attentive competitors and Postscript alternative guides compare the dedicated SMS vendors.
2. Write the signup disclosure first, with the written-consent elements, the frequency promise and links to terms and privacy, then send the confirmation text before anything else and store the consent record: CTIA lists timestamp, medium, the wording shown and the phone number among the data to keep.
3. Wire every opt-out path: the seven words, plain-language replies, and any other reasonable request, honored within ten business days and suppressed across every tool that can text.
4. Store each shopper’s time zone and enforce 8 a.m. to 9 p.m. in it, with a narrower window where counsel advises.
5. Decide frequency and content per shopper below the promised ceiling.

Where Relvino fits

Relvino decides per shopper across email, SMS and pop-ups in ~80ms, inside guardrails the brand sets once: quiet hours in each shopper’s time zone, consent and suppression, and frequency limits. Within those limits it chooses whether a shopper gets a text, an email or nothing at all. The comparison with a flow-based setup is in the Klaviyo vs Relvino guide.

The useful habit from all of this is a short one: before adding a line to an SMS playbook, write down which of the three rulebooks it comes from. If the answer is none, it is a choice the brand gets to make, and should make deliberately.

Frequently asked questions

Is SMS marketing illegal?

No. SMS marketing is legal in the United States when the sender has the right consent and follows the rules on timing and opt-outs. What makes a program unlawful is texting people who never agreed in writing, texting outside permitted hours, or ignoring a stop request. Oklahoma’s 2022 act gives the same remedy as Florida’s, actual damages or $500, whichever is greater, and lets a court raise it to as much as three times that for a willful or knowing violation.

What is an example of an SMS?

An SMS is a short plain text message sent to a phone number, such as “Brand: Your order has shipped and should arrive Thursday.” Longer messages are split into segments, and a message with an image is sent as MMS instead. In marketing, an SMS usually carries the brand name first, one short point, a link, and opt-out instructions.

What is the best SMS marketing tool?

The right tool depends on where the rest of the program runs. Email platforms that added SMS keep both channels and one customer profile in one place; dedicated SMS vendors focus on list growth and texting features. Either way, check that the tool registers the brand for 10DLC, stores consent records with timestamps, honors every opt-out word, and enforces quiet hours in the recipient’s time zone, since those are the obligations.

Can you give me some examples of SMS notifications?

Common SMS notifications in ecommerce are order confirmations, shipping and delivery updates, back-in-stock alerts, appointment or pickup reminders, and account security codes. Most are informational rather than marketing, which matters because the federal written-consent rule is tied to advertisements and telemarketing. If a shopper has agreed to several kinds of texts and replies STOP, the federal rule lets the one confirmation text ask whether the request covers all of them; until the shopper answers, every text that needs consent stops.

How many SMS marketing messages per week is too many?

No federal rule sets a weekly number. The practical ceiling is the frequency the signup disclosure promised, since that is what the shopper agreed to, and a steady rise in opt-outs after sends is the clearest sign a list is getting more than it wants. A brand can promise a range, such as up to a few messages a week, and then send fewer to shoppers who rarely buy.

How long does it take to migrate SMS marketing to Relvino?

The technical cutover takes about 30 minutes: connect the Shopify store, point the sending domain, connect SMS, and shopper data ingests automatically. The brand sets quiet hours, consent rules and frequency limits once as guardrails instead of rebuilding SMS flows. Revenue is then measured in a 14-day pilot beside the current setup, so the switch is judged on results rather than on the day it goes live.