How to use dynamic blocks to collect SMS consent

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You will learn

Learn how to collect SMS consent from shoppers with a form that shows a tap-to-text option on mobile devices and a phone number input field on desktop devices. You will create this with dynamic blocks, which can be configured to appear on some devices, but not others. This allows you to create a single form that shows different opt-in methods to shoppers depending on what device they are using.

When collecting SMS consent, mobile shoppers are more likely to subscribe through tap-to-text, while desktop shoppers prefer to input their phone numbers. Dynamic blocks ensure that you show mobile and desktop shoppers the best way to give their consent, while you grow your SMS audience from one form. 

Before you begin

Note that in order to use SMS marketing in Klaviyo, you must have SMS set up in your account. If you do not have SMS set up and attempt to publish a form that collects phone numbers, it will  prompt you to set up SMS  with the below error message. 


If you ignore the message and still publish the form, you will only collect phone numbers from desktop shoppers. However, you cannot use SMS marketing to text them as the form will not  collect SMS consent from shoppers. Learn more about how to get started with SMS.

Use dynamic blocks to collect SMS subscribers

Rather than creating multiple sign-up forms that are optimized for mobile or desktop, you can instead create a single form that will show mobile shoppers a tap-to-text button, and show desktop shoppers a phone number input field. Set this up with dynamic blocks:

  1. Navigate to the Sign-up forms > Create Sign-up form.
  2. Choose to Build from scratch. This will bring you to a blank template in the editor, which already has an email opt-in step configured. 

    Note that if you choose a multi-step template from the sign-up form library that collects both email and SMS consent, it will already have the SMS Opt-in step optimized on each view, and you will not need to configure this block. Learn more about using dynamic blocks to edit the appearance of your form on mobile and desktop.

  3. In the editor, click on Targeting and Behavior
  4. Under Devices, select All Devices. This configures your form to show up on both mobile and desktop devices.
  5. Click + Step > SMS Opt-in to create a multi-step form that collects both email and SMS consent. 
  6. Choose a list for your new SMS subscribers.
  7. Click Add Step.
  8. From here, you can use the view selector in the top right corner to switch back and forth between desktop and mobile views of the SMS Opt-in step. Click on the desktop icon.
  9. Click on the phone number input field in the preview and set it to show on Desktop devices only. Do the same for the SMS disclosure language, and the submit button.

    Note that when you set a block to show only on desktop devices, it will not be visible on the mobile view. The mobile view will show mobile-only and all-device blocks, while the desktop will show desktop-only and all-device blocks.

  10. Use the toggle in the corner to switch to the mobile view and click Add Blocks.
  11. Drag a new button into the preview, and set the Action to Subscribe via SMS. This creates the tap-to-text call to action.

    Because tap-to-text functionality is optimized for mobile devices, this SMS block will automatically be set to show for shoppers on mobile devices only.

  12. Customize your Subscribe Keyword and Subscribe Message for your tap-to-text call to action.
    • Subscribe Keyword
      If you have several numbers available in your account, the destination number will be automatically selected in the priority order of short codes, toll-free numbers, and long-numbers; then, sorted newest to oldest.
    • Subscribe Message
      By default, this will read "Send this text to subscribe to <organization_name>!", but you can configure the message content. This field allows up to 160 GSM-7 characters, and 1 message only.
  13. Under Sending Region, choose the appropriate phone number for the region you'd like to target.
  14. When someone subscribes via your tap-to-text form, they’ll automatically be brought to their messages app with the subscribe message. They can change this text, but as long as the subscribe keyword is present, they will be added to the specified list.
  15. Now that you have dynamic blocks configured for collecting SMS consent based on device, click back through each step of your form and customize the default text and style so the design matches your brand.

    Make sure that you customize both the mobile and desktop views for each step, if they differ. Learn more about using dynamic blocks (i.e., text blocks, image blocks, etc.) to configure the look of your form to create a distinct view for mobile shoppers compared to desktop shoppers.

  16. Once you’re satisfied with the design of your form, click Publish.

When your form is live, the dynamic blocks you configured will automatically optimize the SMS opt-in experience for shoppers on each device. Mobile shoppers will see a tap-to-text call to action, and desktop shoppers will see a phone number input field and submit button.

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