Guide to Collecting SMS Subscribers

Last updated at:


If you're just starting off with SMS marketing, the first step in a successful text messaging strategy is acquiring subscribers to reach out to. Even if you've been using Klaviyo to send your emails, this does not necessarily mean that you can start sending these same subscribers SMS messages, since SMS consent must be collected separately from email. For this reason, it's important to have a plan in place to start collecting phone numbers and consent from interested contacts. There are two ways you can accomplish this:

  • Starting from scratch
    This will allow you to build your presence with brand new subscribers and continue to grow your list over time.
  • Gaining text messaging consent from your existing email subscribers (if applicable)
    If you've been using Klaviyo to send emails, you likely have a number of subscribers already in your account. These contacts have already shown interest in your brand, so they're a great group to leverage when trying to build your SMS presence. 

In this guide, we discuss how you can execute each of these tactics. If you already have an existing group of SMS subscribers, you will want to import them into Klaviyo before you start growing your list so that you can use them as a starting point.

Note that Klaviyo will not store consent until SMS is enabled, so you must set up SMS before you can begin collecting consent.

Collect New SMS Subscribers from Scratch

Using Klaviyo signup forms, you can collect consent from anyone who visits your website.


Our Guide to Collecting SMS Consent will walk you through two ways to collect brand new SMS subscribers:

  • Use a signup form to collect SMS subscribers
    If you already have a signup form live on your site, you can add a phone number input block to  your form to start collecting SMS consent along with email addresses and other properties from your site visitors. Otherwise, you can create a new form and start collecting opted-in phone numbers and, optionally, additional inputs.
  • Use a click-to-text form to turn mobile browsers into SMS subscribers
    A click-to-text form is a form that shows to those browsing your mobile site. All these subscribers need to do is click a button and confirm that they would like to receive text messages from your brand.

Get SMS Consent from Your Email Subscribers

An existing, engaged group of email subscribers is a great place to start when building your SMS strategy. There are several ways you can reach out to your existing subscribers to ask for their permission to receive SMS messages. You may choose to use all of these techniques or some combination of them.

Note that it's possible for a person to have separate email and SMS profiles. If a phone number is collected and there is no email associated with it, this will create a phone-number-only profile. Similarly, if a phone-number-only profile exists, and the same person enters their email, without entering their phone number and without being cookied, this will create a separate email-only profile. If you identify that a single person has separate email and SMS profiles, you can check out our article on Delete, Merge, and Export a Profile to merge the profiles.

Add an SMS Banner to Your Emails

Please note this feature will not work with Gmail and Outlook. You can use a show/hide block to ensure that your Gmail and Outlook users will not see this block. 

A simple, evergreen way that you can prompt email subscribers to sign up for SMS messages is to include a banner in all of your emails. Specifically, be sure to include this banner in:

  • Welcome series emails
  • Campaign emails (sales, product announcements, etc.)
  • Post-purchase emails

Anyone can add a text banner to their emails. This section explains how to create a clickable banner that opens a text message on the user’s phone. Note that this feature does not work in Gmail or Outlook, so in those cases, the recipient would have to open the text manually. 

Contacts who do subscribe using this method may create duplicate profiles if the same phone number is not already associated with their email profile. Klaviyo does not charge customers for active, phone number-only contacts. Learn more about how Klaviyo merges email and text contact profiles.

In the example below, we'll walk through adding this banner to a template for one of our campaign emails. First, we'll need to open the email template.

Drag in a text block that reads "Text JOIN to [your sending number]." You can find your account's sending number by going to Account > Settings > SMS.


In Block Styles, set the block to display only on desktop. Note that anyone viewing on a desktop would need to manually input your number into their phones.

For mobile viewers, you'll want to link the text so that they can subscribe via one-click, similar to a click-to-text form. To do so, follow the steps below. 

Copy the text block with your phone number. Edit the source of the copied text block so that you can hyperlink the text. Copy and paste the snippet below into the text source. Be sure to replace "[YOUR-SENDING-NUMBER]" with your sending number. Additionally, you must include "JOIN" in the URL in order for customers to be properly subscribed after they tap the link.

<a href="sms:+1[YOUR-SENDING-NUMBER]?&amp;body=Text JOIN%20to%20subscribe%20to%20SMS%20Updates!%20"> Click to join!</a>

When inputting your sending number, separate digits with hyphens in the +1-XXX-XXX-XXXX format. The text that is after the href tag is the text that will be displayed to visitors. You will likely want to change the text from the desktop version to make it clear to recipients that they can join your SMS list simply by tapping the banner.


Next, go to the Block Styles tab and set the block to only display on mobile devices. Once you have your template styled the way you would like, you can save these blocks to use in future flows and campaigns.


Pro tip: after you've created the block once, you can save the block to reuse in other templates.

Send a Campaign Directing Subscribers to a Landing Page

You may also want to send out an email invitation specifically aimed at encouraging email subscribers to sign up for SMS marketing. To do this, you will first want to create a landing page on your website or determine a page on your site where you want to allow contacts to sign up.

Next, create an embedded form to paste on your site. Configure the submit button to feed into your main list of subscribers (likely the list that you are sending this campaign to).


Add consent language onto the form to ensure that you comply with TCPA laws -- you can copy this language from the publish modal when you go to publish your form. Remember to update the links to your company's Terms of Service and Privacy Policy.


Once your form is published, copy the embed code from the Behaviors tab.


When editing your site's theme files, you must paste this embed code on your site exactly where you would like the form to appear. Learn more about how to find where to paste a form's embed code

Once you have the form posted on a page on your site or a landing page, copy the URL of the page. Next, navigate back to your Klaviyo account and create a new campaign from the Campaigns tab. You can create a new campaign from scratch or use one of your prebuilt templates.

Add a call to action (CTA) button to your template. This button should link to the landing page or page on your site where you pasted your embed code. You may even want to consider offering a discount or other incentive to encourage recipients to sign up. If you do offer a discount, you can use either static or unique coupon codes in SMS messages. You will then need to configure your SMS welcome series to include the coupon code.


Then, schedule the campaign to send out to your main list of subscribers. The workflow for subscribers will be as follows:

  1. They receive the email
  2. They click the call to action
  3. They're brought to your landing page with the embedded form
  4. They enter their phone number and submit the form
  5. If your list is set to double opt-in, which all Klaviyo lists are by default, they will confirm their SMS subscription by texting "YES"
  6. The customer will receive the first text message you configure in your welcome flow, which, optionally, contains a static coupon

Use a Signup Form to Collect SMS Consent from Existing Subscribers

If you have an existing base of email subscribers, you can target a form to display to these contacts when they browse your site. By only asking for their phone number, you can cut down on the number of questions you ask on the form.

First, clone or create a new signup form with a phone number input field. Target this form to only show to people who are already on your email list in the Behaviors tab. Under the targeting options, select Target visitors in a list or segment and then check Show to visitors in certain lists and segments. Here, specify that someone is on your main list already.  


Because these contacts have already subscribed to your main list, you don't need to include an email input on the form. You may simply delete this block and, when someone subscribes, they will receive a double opt-in confirmation text if your list is set to double opt-in.

Additional Resources

Was this article helpful?
96 out of 119 found this helpful