Guide to collecting SMS consent

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You will learn

Learn about SMS consent, including what counts as SMS consent, how you can collect it, and how resubscribes work. SMS consent refers to whether someone is opted in (i.e., if they have agreed to receive marketing text messages from your brand). 

What counts as SMS consent

SMS is more regulated than most other marketing channels. Due to this, there are stricter requirements on what counts as proper SMS consent. Below, we break down what you need to do for SMS. 

Individuals must explicitly agree to receive SMS marketing messages

Someone must agree to receive SMS marketing messages from your brand. Typically, someone subscribes by checking a box at checkout or signing up through a form. 

SMS consent also must be collected separately from any other marketing channel. For instance, while you can collect both email and SMS consent in the same form, you must use a separate opt-in button for SMS. 

You cannot force SMS consent

It’s illegal to force someone to sign up for SMS in order to make a purchase. 

Additionally, providing consent for SMS cannot appear as if it’s required. Even if giving SMS consent is optional for your customers, you may face fines or compliance issues if SMS consent seems required. For instance, collecting both SMS and email consent on a single-page form is not recommended, as customers may think they have to sign up for SMS if they want to sign up for email. 

Use disclosure language wherever you collect SMS consent

SMS subscribers must understand what they’re agreeing to before they sign up. To make this clear, include disclosure language wherever you collect SMS consent, whether that is on a checkout page, form, banner in an email, or a third-party quiz or form (when using APIs to send consent). 

Use double opt-in for an SMS abandoned cart message (US)

If you plan to send an SMS abandoned cart reminder to anyone in the US, you must use double opt-in when collecting consent. 

Double opt-in is always recommended, but in the US, it’s also legally required. For more information on US laws for SMS, please read our article on understanding US SMS compliance laws


Does having someone’s phone number count as consent for SMS?

No. If someone gave you their phone number, that does not mean they gave you permission to send them SMS. While you do need a phone number to text someone, they also must explicitly say they want to receive marketing text messages. 

Does having consent for email count as consent for SMS?

No. Having consent for email does not mean you have consent for SMS. Individuals must opt in to SMS marketing specifically; opting into any other marketing channel (including email) does not count as consent for SMS. 

Should I use the same opt-in checkbox or button for both email and SMS? 

No. You risk falling out of compliance if you, for example, have a single checkbox to gather consent for both email and SMS. As a best practice, you should always use a separate checkbox or button for SMS consent. 

Should I use a general “agree to marketing” checkbox or button for SMS? 

No. It’s best to have a checkbox or button specifically for SMS. A general “agree to marketing” option is not considered sufficient for SMS in most countries. 

Should I use a single-page or multi-step form when collecting both email and SMS consent?

Multi-step forms are the best option for collecting both email and SMS consent because they allow you to collect SMS consent separately from email consent. 

Single-step forms are a potential compliance issue, as it may appear you are forcing the customer to sign up for SMS in order to access email marketing. Thus, they are not recommended. 

Where should the disclosure language go in a form? 

You should put the disclosure language above the SMS consent checkbox or button. That way, people see the disclosure language before they opt in. 

How to collect consent

There are several different ways you can collect SMS consent. 

A few of these options should be done when you first start with SMS, while others can be left for later or only in certain scenarios. Because of this, we’ll break them down into 3 categories: 

  1. Basic (what everyone should do as soon as they start with SMS)
  2. Intermediate (what you can leave for later)
  3. Advanced (what only select users should do)

We'll briefly cover the different methods for collecting SMS consent in this article and link to other, more detailed articles for step-by-step instructions for when you're ready to build your consent channels!

Basic methods

These are actions everyone should take when they first set up SMS. There 2 basic forms of collecting SMS consent:

  1. Create popups that target new subscribers and your current email subscribers (estimated time: 10–15 minutes).
  2. Collect SMS consent at checkout for your ecommerce store: (estimated time: 10 minutes).
    1. BigCommerce
    2. Magento 2
    3. Shopify
    4. WooCommerce
Why use popups? 

Creating popups that collect SMS consent makes it easy for anyone visiting your website to sign up. Popups are one of the most common ways of gathering subscribers, and you can use them to target those who are brand new or already email subscribers. You can also create tap-to-text (also called click-to-text) forms to make it easy for anyone on a cell phone or tablet to subscribe.

We strongly recommend using a multi-step form if you’re collecting email consent at the same time as SMS consent. SMS consent can’t appear required or be bundled with consent for other marketing channels, so you risk falling out of compliance with single-page forms. 

Why collect SMS consent at checkout? 

One of the quickest and easiest ways to grow your SMS list is by collecting consent at checkout. Consent at checkout offers you a non-intrusive, streamlined, and easy way for customers to sign up. With Klaviyo’s integrations, you can leverage this approach and reach a wider audience with your SMS marketing.

Intermediate methods

These consent methods don’t need to be done as soon as you set up SMS. Instead, wait until you have finished setting up the basic consent collection steps, key SMS flows, such as your SMS welcome, abandoned cart, and post-purchase flows; and the rest of the steps recommended in our Getting started with SMS course.

  1. Use emails to collect SMS consent (estimated time: 10 minutes).
  2. Collect SMS consent via Instagram stickers (estimated time: 5–10 minutes).
    Note that these steps are only for businesses who are already using Instagram.
How can you use email to collect SMS consent? 

If you have a current list of email-only subscribers, you can ask this group to sign up for SMS as well. In particular, your highly engaged subscribers and your VIPs are great groups to target. 

There are 2 approaches to using email to gather SMS subscribers. 

  1. Link to an embedded form within the email.
  2. Create a click-to-text banner to use in the email.
    Note that these banners would only work if the recipient opens the email on a mobile device and is not using Gmail or Outlook.

Both approaches are discussed in How to use an email to collect SMS consent.

How can you use Instagram stickers to gather subscribers?

You can create an Instagram sticker that redirects to a landing page. Thus, you can potentially gather consent from anyone who sees the sticker. 

Typically, we only recommend this approach if you already established an Instagram following. 

Example of an Instagram sticker with a link to collect SMS consent

Advanced methods

Advanced consent collection methods require a developer or someone experienced with making API calls. 

Using Klaviyo’s List API is particularly helpful if you’re using a third-party sign-up form to collect SMS consent and want to transfer this consent into Klaviyo. You can also use this API to send information from a quiz. Note that you still need proper disclosure language wherever you collect consent, including if you’re using the API. 

Note that for some third parties (including Privy and Justuno), you don’t need to set up the API call yourself, as they will sync SMS consent to Klaviyo via an integration.

Resubscribing to SMS

Depending on how someone opted out, they may need to resubscribe in a certain way. Note that for the "UNSTOP" and "START" keywords, you must have a list titled "SMS Subscribers." The capitalization must match exactly as shown here. 

If you have a toll-free number someone previously texted "STOP," the only way for them to be resubscribed is for them to text the word "UNSTOP." This is required by wireless carriers in order for them to deliver messages. If they use some other method to resubscribe, the profile will show the individual as opted in, but wireless carriers will not deliver any messages to that recipient until they text the word "UNSTOP."

If your customer did not opt out via the “STOP” keyword, and instead used an unsubscribe link, they can resubscribe using forms, UNSTOP, or via checkout. Similarly, if you have a short code, your customers can resubscribe by any method. 

Additional resources

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