Your complete guide to SMS compliance in 2025
Essential SMS compliance requirements and best practices
Summary
What is SMS compliance?
SMS compliance centers around three key areas: obtaining proper consent, creating appropriate content, and following message sending rules.
This guide breaks down essential requirements including explicit opt-in procedures, prohibited content guidelines, and regional messaging restrictions. While requirements vary across regions, the goal remains consistent: creating a positive customer experience while adhering to both legal requirements and wireless carrier policies.
This information is intended solely for educational and informational purposes and should not be construed as legal advice. The content provided is general in nature and may not reflect the most up-to-date information. Klaviyo strongly advises consulting with a qualified legal counsel to ensure your compliance with applicable laws and regulations in connection with your use of our services.
What do you think of when you hear “SMS compliance”? Like many, you may feel overwhelmed, visualizing complex legal speak or overly stringent rules.
At its core, though, SMS compliance is simply the enforcement of best practices to help provide a positive customer experience and promote long-term growth.
Compliance guidelines come from actual laws governing the use of SMS as well as wireless carrier and industry policies.
The guidelines often overlap, although some carriers and regions approach the same topics differently or ask for more precautions than others.
In general, compliance applies to 3 areas of SMS:
1. Collecting and removing consent
2. Creating content
3. Sending messages
Here, we walk you through the major compliance principles that cover each of these categories, including definitions, regional differences, and examples.
1. Collecting and removing SMS consent
Key concepts around SMS consent
All of the following are required by law in most countries, or at least are very strongly recommended:
• Getting explicit consent
• Making SMS optional
• Including disclosure language
• Using double opt-in
• Allowing opt-outs
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Explicit consent (also called express consent) |
Individuals must directly tell you that they want to receive SMS marketing messages from your brand. |
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Disclosure language (also called a disclaimer) |
This informs users about your SMS marketing program, and should be used anywhere you collect SMS consent. The language needed may vary by country, especially if you plan to use a short code. |
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Optional consent |
SMS consent must always be optional. You cannot require it, or even appear to require it. |
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Separate SMS consent |
This means consent for SMS is not bundled with consent for other marketing channels. A best practice is to use a separate action, such as a separate checkbox, button, input field, or other similar option to collect SMS consent. |
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Double opt-in |
Double opt-in is the general practice of confirming a recipient’s subscription to SMS. In other words, double opt-in confirms that a phone number belongs to the individual who entered it and therefore that the person who owns that phone number really intends to sign up for your SMS program. This process means taking 2 distinct actions; e.g., entering a phone number, then sending or entering a confirmation text or code. |
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Allow opt-outs |
The 2 most important aspects of a compliant opt-out setup are:
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Opt-out instructions |
Details how someone can opt out of SMS, based on the sending number you’re using:
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Consent compliance in action
When we break it down, SMS consent compliance makes sure any potential subscriber:
• Provides consent specifically for SMS
• Knows that providing consent is optional
• Is informed about what opting in means
• Can opt out at any time
Providing consent specifically for SMS marketing
The first part of this is simple: don’t text anyone who hasn’t explicitly opted in to SMS marketing.
It’s important to keep in mind that consenting to SMS marketing is not the same as someone:
• Sharing their phone number (without specifically saying they wanted SMS marketing)
• Signing up for another channel, such as email or mobile push notifications
Users should always know that they are signing up for SMS marketing messages.
Showing SMS consent is optional
You should never “require” SMS consent, such as by making it a condition of purchase.
What’s more, users should understand that signing up for SMS marketing is their choice. This is one reason having “separate SMS consent” is important. If you bundle the opt-in for SMS with something else (like email), users may feel like they “have” to sign up for text message marketing. On the other hand, by asking for SMS consent via its own page, checkbox, button, or other action, it’s always clear that the opt-in is for SMS marketing and is optional.
But if you want to use a single form or page for multiple channels, you need to make it clear that consenting to SMS isn’t required.
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Do’s |
Don’ts |
|---|---|
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Explain SMS consent is optional in your disclosure language. |
Require SMS consent in order to place an order, create an account, or receive critical information. |
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Ask people to confirm the subscription (i.e., use double opt-in to confirm that the number belongs to them). |
Pre-fill checkboxes for SMS consent on pages or forms. |
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Allow users to exit away from pages or forms collecting SMS consent. |
Hide ways to close the form or navigate away from the page. |
Informing your audience about opting in
Your shoppers not only need to be willing to opt in to SMS, but they also need to be informed. Including compliant disclosure language plays a major role in both of these goals.
A best practice is to place this language above any button or checkbox where someone consents to SMS.
Note that the requirements for what to include in your disclosure can vary, particularly when it comes to applying for short codes. At minimum, it’s generally best to include:
• Your organization, brand, or SMS program name
• That consent for SMS is optional
• Details about your SMS program’s messages, like the types and examples of the texts you plan to send, which can include: promotional/marketing, transactional, US: cart abandonment or sweepstakes (short codes only); How often you’ll send texts; That texts may come from an autodialer
• How to get help or to opt out
• Links to your terms of service and privacy policy
• Visit our Help Center to learn how to create disclosure language.
Visit our Help Center to learn how to create disclosure language.
In Klaviyo, the best opt-out option is applied by default so your recipients can easily unsubscribe.
Allowing opt-outs at any time
Your subscribers should always know how to opt out of your SMS program. This information should be in your disclosure language where someone signs up, and it should regularly appear in your SMS messages.
A best practice is to regularly include opt-out instructions in your text messages. You should also make sure that every SMS subscriber, even those who are unengaged, gets at least 1 text a month that includes unsubscribe instructions. This way, you’re regularly providing a way to opt out.
Depending on your sending number, you can provide opt-out instructions either through:
• An unsubscribe link, which is the best option for branded sender IDs
• An opt-out keyword (like “STOP”), which is the best option for all other number types
The only true difference between these options is that keywords don’t work for branded sender IDs, as this number type can’t receive inbound text messages.
2. Creating SMS content
Key concepts around SMS content compliance
There are 3 key themes when it comes to content compliance:
• Including opt-out instructions
• Avoiding prohibited content
• Identifying your brand
Since we’ve already discussed opting out, we won’t go over it again. But remember that you need opt-out instructions when you are creating your SMS content.
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Concepts |
Definition |
|---|---|
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Prohibited content |
Any content that you cannot reference or link to in SMS. What’s considered prohibited varies between countries. |
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SHAFT |
Stands for: sex, hate, alcohol, firearms, and tobacco. This category is either prohibited or has heightened restrictions (e.g., age gating), depending on the sending region. |
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Age gating |
A technical protection method used to prevent underage people from receiving restricted or inappropriate content. This checks that someone is of legal age in their country before being able to sign up for your SMS program. |
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Identifying yourself in a text |
Telling recipients the name of your brand, organization, or SMS program within a text. |
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Organizational prefix |
Adding the name of your brand, organization, or SMS program at the very beginning of a text. (e.g., “Bola Baked Goods: Fresh in stores…”). This is a common way for brands to identify themselves in SMS messages. |
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Branded sender ID |
A type of SMS number that you can customize to be your brand or organization name. This is a way senders can identify themselves in a text. |
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Company information |
A way to both identify your brand and share how customers can reach you. This information must include a valid mailing address and at least one way to contact an agent or leave a message for someone at your company (e.g., email address, website, or phone number). |
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Opt-out instructions |
Details how someone can opt out of SMS, based on the sending number you’re using: |
SMS compliance tip: use a trusted SMS provider, like Klaviyo, that checks for prohibited content and has functionality for you to automatically identify your brand.
Best practices for avoiding prohibited content
In certain cases, regulated content may be allowed for SMS with age-gating. Klaviyo, for example, allows age-gating for alcohol in the US, Europe, and Australia.
Alternatively, if you are approved for a short code, you may be allowed to send certain content that otherwise would not be allowed. Keep in mind, though, that every country has its own regulatory body for short codes, so being approved in 1 country may not mean you will be approved in any other region.
For all other cases, it’s best to avoid prohibited content in your SMS messages.
Best practices for identifying your brand
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Prohibited content |
US |
Canada |
Europe |
Australia |
New Zealand |
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Organizational prefix or branded sender ID | |||||
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Company information | |||||
Consent compliance in action
Let’s use our themes to frame content compliance and how it applies in the real world:
• Knowing what’s prohibited
• Identifying your brand
Knowing what’s prohibited
“Prohibited” content goes beyond the strict letter of the law. Even if content isn’t strictly illegal under applicable statutes or regulations, the subject could still be highly regulated, restricted to certain ages, or considered too risky for text message marketing.
Most of what’s considered prohibited might be what you expect, like illegal substances; MLMs; gambling or debt collection; and, of course, SHAFT. But a few topics may surprise you:
• Fireworks
• Vaping
• CBD
• Any weapon or equipment (like holsters)
These all have ties to SHAFT, and thus are heavily regulated.
Context is important. If you have a restaurant supply store, wireless carriers typically won’t consider your messages about kitchen knives and wine glasses as being related to weapons or alcohol. But this is not guaranteed, so keep a careful eye on your deliverability metrics if you sell any of these types of items.
In addition, you may have better luck with sending messages that contain heavily regulated content if you send from a short code. This is because the registration process is fairly strict; as a result, wireless carriers tend to trust messages from short codes. Thus, a business is less likely to experience heavy filtering with a short code than with any other number.
Another option is age gating. Age gating checks that someone is of age before applying consent. For instance, Klaviyo allows age gating for alcohol in most countries where SMS is available, although there are exceptions.
Identifying your brand
Of these, simply referencing your brand within an SMS is not recommended. While it may save characters compared to an organizational prefix, the prefix is better, as it identifies the sender immediately and provides a consistent consumer experience.
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Ways to indicate your brand |
Examples |
|---|---|
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Adding an organizational prefix |
 |
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Using a branded sender ID |
 |
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Providing company information, either within the text or by linking to these details (required in Canada and New Zealand) |
 |
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Referencing your brand within a text |
 |
3. Sending SMS messages
Key concepts around sending SMS messages
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Concepts |
Definition |
|---|---|
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Quiet hours |
Times or days where sending SMS marketing messages isn’t allowed. |
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Waking hours |
The opposite of quiet hours: times or days where sending SMS marketing messages is allowed. |
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Messaging limit |
The number of messages allowed in a given period of time, typically 24 hours. |
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Promotional (marketing) |
Telling recipients the name of your brand, organization, or SMS program within a text. |
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Transactional |
Promotional messages are business-driven. Typically, they aim to generate sales or collect information, such as by advertising a product/deal or asking someone’s preferences. |
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Branded sender ID |
Transactional messages are user-driven and provide important information about a specific action the person took. They are operational touchpoints that users expect, such as order confirmations, shipping updates, and log-in resets. |
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Compliance |
Required regions |
Details |
|---|---|---|
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Quiet hours |
All countries |
Quiet hours vary by region, but generally don’t send before 8 a.m. or after 8 p.m. |
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France |
Don’t send promotional messages before 8 a.m., after 10 p.m., all Sundays, or on public holidays. | |
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Messaging limit: |
US |
Each person can only receive a single SMS message about a cart abandonment. And that SMS must be sent within 24 hours. |
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Messaging limit: |
Florida |
Limit is 3 SMS for a certain product or marketing campaign/per person within 24 hours. |
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Oklahoma, |
Limit is 3 SMS/per person within a rolling 24-hour period. | |
Sending SMS compliance in action
When it comes to sending compliance, it’s all about keeping your recipients (and where they live) in mind by:
• Brushing up on local quiet hours
• Choosing what to send (and when)
• Adhering to cart abandonment guidelines (US)
Quiet hours change from place to place.
For instance, in most of the US, quiet hours are before 8 a.m. and after 9 p.m. But certain states extended quiet hours to start at 8 p.m., including Florida, Washington, Oklahoma, New Jersey, and Maryland. Furthermore, Connecticut’s quiet hours are the longest: before 9 a.m. and after 8 p.m.
In most countries, quiet hours are the same each day, and you can technically send during those hours. But in France, quiet hours extend to all Sundays and public holidays, and wireless carriers refuse to deliver messages during quiet hours.
Wherever you plan to use SMS, look into the quiet hours for that region. This helps you learn about small differences between countries and can inform your marketing strategy (e.g., not trying to target your French audience on a Sunday).
You can also use tools to ensure you only send during waking hours. For campaigns, target only certain countries for a message or send based on a recipient’s local timezone. As for non-transactional flows, delay messages during quiet hours.
Compliance differences between countries
All regions
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Collect or remove consent |
Create SMS content |
Send SMS messages |
|---|---|---|
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Get explicit consent for SMS: |
Avoid prohibited content or make sure you use age gating. |
Observe local quiet hours. |
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Include disclosure language anywhere you collect consent. |
Identify your brand in your SMS messages. |
Limit the number of SMS to <3 per 24 hours. |
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Use double opt-in. | ||
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Respect opt-out requests. | ||
United States
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Region/state |
Law/regulatory organization |
Law/regulatory organization |
|---|---|---|
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All |
• Telephone Consumer Protection Act (TCPA) |
Observe quiet hours: 9 p.m. to 8 a.m. |
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Florida |
Florida Telephone Solicitation Act (FTSA) |
Cart abandonment message limit: 1 SMS per recipient sent within 24 hours |
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Oklahoma |
Oklahoma Telephone Solicitation Act (OTSA) |
Quiet hours: 8 p.m. to 8 a.m. |
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Washington |
Washington HB 1051 |
Quiet hours: 8 p.m. to 8 a.m. |
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Connecticut |
Public Act No. 23-98 |
Quiet hours: 8 p.m. to 9 a.m. |
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Maryland |
Senate Bill 90 |
Quiet hours: 8 p.m. to 8 a.m. |
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New Jersey |
Bill S921 |
Quiet hours: 8 p.m. to 8 a.m. |
Canada and New Zealand
|
Region |
Law |
Unique compliance considerations |
|---|---|---|
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Canada |
CASL |
Include company information (such as address) in every SMS. |
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New Zealand |
UEMA | |
In addition, age gating for alcohol may not be available.
France
Quiet hours for France are different than in other regions. Whereas you are responsible for not sending promotional message during quiet hours in other regions, French wireless carriers don’t deliver promotional SMS:
• Before 8 a.m.
• After 10 p.m.
• On all Sundays
• During public holidays
Germany, Austria, and Switzerland
Double opt-in is always recommended, especially for SMS.
That said, in some European countries, it’s an even stronger recommendation than normal. In Germany, Austria, and Switzerland, double opt-in is the preferred way of demonstrating that consent has been properly and lawfully obtained.
Keep SMS compliance in mind with Klaviyo
Prioritizing SMS compliance is essential to the success of your text message program. It’s about more than legal requirements: it’s about the best practices that help you grow your subscriber list, create a positive customer experience, and ultimately drive your revenue.
With Klaviyo, you have access to many tools and features that are designed to set you up for SMS compliance. You can use these as your foundation for your SMS strategies, optimizing and personalizing as you build your SMS program.
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