Migrating from Another SMS Provider to Klaviyo

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Migrating from another SMS provider strengthens your ability to create a truly customized experience for your customers. Importing your SMS contacts will allow you to centralize your customer data so you can leverage Klaviyo’s robust analytics. You can also tailor your customers' experience through the use of flows that integrate SMS, email, and push notifications.

This guide will walk you through migrating your data from another SMS provider to Klaviyo.


Follow these steps to migrate from another SMS provider to Klaviyo:

  1. Choose an SMS plan
  2. Export SMS contacts
  3. Format your contact list
  4. Upload the SMS contact list into Klaviyo
  5. Export additional data
  6. Migrate third-party signup forms into Klaviyo
  7. Point your forms to a Klaviyo SMS opt-in list
  8. Begin using SMS in your flows and campaigns

Choose an SMS Billing Plan

When you enable SMS in Klaviyo, you'll be prompted to choose an SMS plan. The plans are based on how many SMS profiles you've texted in the last month as well as how many messages you've sent. Sending numbers are included, and you can either have one randomly assigned to you or port one into Klaviyo. 

Export SMS Contacts

Before you begin the process of migrating your SMS contacts into Klaviyo, it's important to distinguish between subscribers who have opted-in to SMS messaging and those who have not. It is against Klaviyo's Terms of Service and TCPA laws to market to contacts who have not explicitly opted-in to receive SMS communication from your business.

Klaviyo does not require that you send a final text out of your current SMS provider as part of the migration process. This is not required for the port to be successful; however, it is considered a best practice. Read this article on how to inform your customers about a change in phone numbers

Klaviyo identifies opt-in subscribers as those who have a phone number and an SMS consent timestamp associated with their profile. Klaviyo will only send SMS messages to contacts who have both a phone number and an SMS consent timestamp stored within their Klaviyo profile.


Primarily, you'll want to export contacts from your previous SMS provider that have opted into SMS messaging.

Most SMS providers allow you to export your contacts in CSV format. Contact your SMS provider for specific instructions on how to export your contacts. If you store both opted-in customers and unsubscribed/opted-out customers within your SMS provider account, be sure to filter for contacts who have opted-in to SMS communications for your primary contact import.

When you designate contact fields to export, be sure to select phone number and SMS consent timestamp. Additionally, you may also want to export first name; last name; address; and any other identifying information like gender, birthdate, etc. You'll have the opportunity to map these fields before you import them into Klaviyo.

Export your data in CSV format.

After you finish exporting subscribers, you may want to separately export contacts who have unsubscribed or opted-out of SMS messaging to be saved outside of Klaviyo for historical reference. Be sure to keep these non-subscribers separate from the contacts you intend to import into Klaviyo.

Format Contact List

Contacts are imported into Klaviyo in CSV format. You should carefully format your CSV file before it's imported into Klaviyo to ensure that your contacts are imported smoothly and accurately.

Open your CSV file. Carefully comb through your list, paying special attention to the column headings:

  • Column headings should be in the first row of the CSV file. If there are additional rows before the column headings, delete these extra rows.
  • You must include a "Phone Number" column. Phone numbers must be in the E.164 (e.g., +12345678910), RFC966 (e.g., +12-34-567-8910), or E.123 national (e.g., 12345678910) or international (e.g., +12 345 678 910) formats. When formatting your CSV, add a ' character before the + character to ensure that the cell isn't autoformatted.
  • If possible, nclude an "SMS Consent Timestamp" column. Timestamps need to be specifically formatted or Klaviyo will not recognize them as timestamp fields. Make sure timestamp data is represented in one of these formats:







  • Include a country column and add the appropriate country value for each phone number; note that you can only import consent for countries where Klaviyo SMS is available.
  • You may also want to include a "First Name" and "Last Name" column.
  • Include any custom profile properties, such as gender, that you'd like to upload into Klaviyo

This is an example of how your CSV file should be formatted:


For more detailed instructions on formatting CSV files, head to our article on Creating and Adding Contacts to a New List.

Import Contact List

Before importing contacts, turn off any flows triggered by the list you're adding these contacts to or any flow triggered by the Consented to Receive SMS metric by setting them to manual or draft. Otherwise, your imported contacts will enter into these flows as soon as they're added.  

After you've formatted your export data, pause any flows that are triggered by a phone number or email address being added to a list by turning all the flow messages to manual or draft mode. This is important to do before importing contacts, or they will receive these flow messages. 


Log into your Klaviyo account and navigate to Lists & Segments. Locate the list where you'd like to upload your contacts. Click the menu to the right of the list and select Import Data.


Drag and drop your CSV file. You will be prompted to review field mapping before Klaviyo begins the import. Carefully review each import field/corresponding Klaviyo field, and modify them as needed. By default, all identified fields are included in the import. You can omit a field from the import by unchecking the box to the right of the field name.

Import fields that are not automatically matched to a Klaviyo field are marked as "Unmapped." If you try to import an unmapped field, Klaviyo will give you an error message and prompt you to map the field.

From the dropdown, select an existing Klaviyo field name or create a custom field by typing a name into the blank entry field. To the right of the field name, select a data type from these options: String, Boolean, Numeric, Date, or List. If you're unsure of the data type, head to our article on data types in Klaviyo.Field_Mapping_2.gif

This is a simple example of field mapping for an SMS contacts import:

When you're finished, click Import Review on the upper-righthand corner of your screen.

Review your selections, taking special note of SMS Consent verification. When finished, click Start Import.

For a deeper dive into importing contacts, head to our article on Migrating Existing Subscribers and Unsubscribes into Klaviyo.

Export Additional Data

You may have data associated with your SMS account that you want to export for historical reference, such as call logs, reports, or account information. Before you sunset your previous SMS provider account, comb through your account and extract anything you may need to reference in the future. Contact your provider's support team if you need help with your export.

Migrate External Signup Forms to Klaviyo

Currently, SMS consent can only be collected through a Klaviyo signup form. If you have forms associated with your previous SMS provider or third-party signup forms, you'll need to re-create those in Klaviyo.

Klaviyo has an intuitive drag-and-drop signup form builder that you can use to recreate your signup forms. You can also custom code a signup form in Klaviyo using our legacy signup form resources. To make life easier, we also offer a form library with pre-designed forms that you can customize for your site.

Once your forms are created, point your forms to a Klaviyo SMS opt-in list.

Learn more about creating signup forms.

Next Steps

Once you're done migrating your SMS contacts, you'll be able to leverage Klaviyo’s powerful SMS tools to create a customized experience for your customers. 

Create an SMS Welcome Series

Just like your customers receive an email when they signup for your newsletter, you can enable a flow for when customers sign up for SMS notifications.

Add an SMS Message to a Flow

Truly customize your customer's experience by incorporating SMS into your flows.

Create an SMS Campaign

Provide valuable and timely content to your subscribers by creating an SMS campaign. 

Find out how to Create and Send an SMS Campaign


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