Migrate from Attentive to Klaviyo

Last updated at:


When migrating from Attentive, you can upload your existing list of SMS subscribers to Klaviyo to start building out your SMS marketing strategy right away. Importing your SMS contacts allows you to centralize customer data so that you can leverage Klaviyo’s robust analytics and tailor your customers' experience with SMS-integrated flows, emails, and push notifications.

This guide will walk you through migrating your data from Attentive to Klaviyo.

Designate an SMS Sending Number

When you enable SMS in Klaviyo, you'll be prompted to choose an SMS plan.

All SMS plans include a free sending number. For lower-cost plans, this is a toll-free number, while for higher plans, it is a short code. Note that you must be approved for a short code, and not all businesses are eligible. Further, the short code approval process can take several weeks, so please allow time for the creation of a new short code when planning your SMS migration.

If you indicate that you already have an SMS number, our Support Team will contact you regarding porting your number over to Klaviyo. Klaviyo does not currently support porting long numbers.

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

Switching from another SMS provider is a great time to re-evaluate and possibly make changes to your SMS number type. For more information, see our guide to choosing an SMS Number.

Export SMS Subscribers from Attentive

Before you begin migrating your SMS contacts from Attentive 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 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 profiles. 

Attentive requires that you reach out to your account representative to receive an export of your SMS subscribers as a CSV file. It is not currently possible to export the file yourself. When migrating to Klaviyo, plan for turnaround time for Attentive to complete this request.

We recommend asking your account rep for a CSV export containing all contacts, including (if available): first name, last name, email address, phone number, and the consent timestamp. At a minimum, you will require the SMS subscriber’s phone number and consent timestamp.

If the CSV file you receive contains contacts who have opted out of SMS messaging, as indicated in the opt_out column of your export, you will want to filter these contacts out before proceeding with an import.

Format Subscriber List CSV

Carefully format your CSV file before importing it into Klaviyo to ensure that your contacts are imported smoothly and accurately.  

Though not required, you will likely want to include these columns in your import, if they have been included in your CSV file:

  • first_name
  • last_name
  • email

 The phone number column is required to import your SMS contacts. Check the format of the phone numbers in your CSV file. Phone numbers must be in one of the following formats:

  • E.164 (e.g., +12345678910)
  • RFC966 (e.g., +12-34-567-8910)
  • E.123 national (e.g., 12345678910) 
  • international formats (e.g., +12 345 678 910)

Klaviyo requires an SMS Consent Timestamp column at the time of import, so you will need to rename the appropriate column heading. Locate the column heading named created, delete the text, and rename it SMS Consent Timestamp. Doing so allows your import to automatically map the values to the correct field in Klaviyo.


Timestamps need to be specifically formatted or Klaviyo will not recognize them as timestamp fields. Attentive exports timestamp data in the format MM-DD-YYYY HH:MM:SS by default. You may wish to format these data fields as dates to ensure proper import. The date format MM/DD/YYYY HH:MM:SS is supported by Klaviyo by default. For additional supported timestamp formats, check out the guide here.

Import Subscriber List to Klaviyo

Before uploading SMS subscribers into Klaviyo, set any flows triggered by the Consented to Receive SMS metric, or by the list you're importing the contacts into, to manual or draft mode. After uploading, wait for about an hour before turning these flows live again. 

After you've formatted your export data, you can import it into a Klaviyo list. To begin, log in to your account and navigate to Lists & Segments.

Click Create List / Segment in the upper right corner to create a new list for your SMS subscribers. Then, select List.

Give your new list a name, such as Attentive SMS Subscribers and click Create List.


Once your new list is created, click Upload Contacts to add your SMS subscribers via import. Drag and drop your CSV file into the field provided, or select it from your computer to upload your contacts. After selecting your file, Klaviyo will process the import and display a green loading bar with the text Uploading and validating file… If any required columns are missing, Klaviyo will alert you with an error message.


If you would like to add the contacts to an existing list, locate the list where you'd like to upload your contacts. Then, click the menu to the right of the list and select Import Data. Drag and drop your CSV file into the field provided to upload your contacts. 


For more detailed instructions on adding new contacts to a list, head to our article on Creating and Adding Contacts to a List.

Whether you create a new list or update an existing list, 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.

Here is an example of field mapping for an SMS contacts import from Attentive:


Import fields that are not automatically matched to a Klaviyo field are marked as Unmapped. If you try to import an unmapped field, an error message will appear, prompting you to map the field. From the dropdown, select an existing Klaviyo field 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.

When you are satisfied with the field mapping, click Import Review on the upper right-hand corner of your screen. Review your selections, taking special note of SMS consent verification. When finished, click Start Import.


Your import will begin shortly. Depending on the length of your contact list, the import may take some time. You can stay on this page to watch the upload progress, but it is not necessary. Klaviyo will send you an email confirmation as soon as the import is complete.

After the import finishes, you will see a summary of the completed import which includes a report of any skipped records. If your CSV file contains improperly formatted data, those fields may fail to import properly. When this occurs, you can download a report of the skipped records, resolve any formatting issues, and retry importing those records.


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

Create a New SMS Segment

When your SMS contacts are successfully imported to a Klaviyo list, create a segment to begin tracking and analyzing your subscribers behavior. 

Navigate back to Lists & Segments. Click Create List / Segment in the upper right corner to create a new segment of your SMS Subscribers. On the next page, select Segment.


Give your new segment the definition: If someone is or is not consented to receive SMS and select is from the dropdown list. Then click Create Segment. To learn more about creating segments for SMS subscribers, check out our SMS Segments guide.

You are now ready to start integrating SMS into your campaigns and flows. Check out the additional resources below for guides on getting started with your SMS strategy. 

Attentive Form Troubleshooting

When redirecting a custom or third party form to a Klaviyo list, it is expected that the form will adhere to your list’s double opt-in behavior. By default, Attentive forms will use a members endpoint from the V2 list API. This is equivalent to uploading a CSV of opt-ins into a Klaviyo list and we would not trigger a double opt-in message to be sent, even if it is enabled at the list level.

In order to have your Attentive form adhere to the list opt-in settings, the endpoint needs to be changed to the subscribe endpoint. We will then treat it as though the user signed up through a signup form and respect the opt-in settings. This redirect must be done by Attentive. You should reach out to Attentive to switch these endpoints on the Attentive end.

Additional Resources

Was this article helpful?
8 out of 9 found this helpful