Upload a List of SMS Contacts

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If you are migrating over from another SMS provider or already have an existing list of SMS subscribers, you can upload these to Klaviyo to start building out your SMS marketing strategy.

Please note that it is required that you have previously obtained consent from these subscribers, otherwise, you will not be able to text them. 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.

If you're not sure if you've collected SMS consent, follow our guide to acquiring SMS subscribers for best practices around obtaining consent from contacts that you may already have in your account.

Format Your List of SMS Contacts

You will need to import your file of SMS contacts as a CSV or via copy and paste from a CSV or Excel sheet. There are two key data points this file must have, represented by headers:

  • Phone Number (required)
    A contact's phone number 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. Please note that it is currently only possible to text US-based subscribers, though you may upload numbers with different country codes. Always include the country code. 
  • SMS Consent Timestamp
    In order to text your contacts, you must have previously obtained consent. This timestamp must be formatted in one of Klaviyo's accepted datetime formats (e.g., 2019-09-01 13:34:08+00:00). SMS consent timestamps can only be set for US numbers, as SMS is currently only available for contacts within the US.

Before you upload SMS numbers, check that you have the country code (e.g., +1 for the USA). Note that you do not need to manually add the plus sign (+) beforehand, as it will automatically be appended at the time of import. If the plus sign is already included, you can stop it from becoming a function by adding an apostrophe in front of the plus (e.g., '+12345678910). 

Add a column that indicates the country (e.g., USA, United States, or US). This column and associated field values are required whenever you don't have the country code, but even when you do, it is a best practice to always include this column. Upon import, map that column to "Country." 

Optionally, you may also add additional headers to this file to map data to existing Klaviyo properties or any desired custom properties. Then, follow the instructions outlined in our general guide to importing lists to add your contacts to Klaviyo.

The following examples are both acceptable formats for the CSV file. 


Map Your Data

After you upload your list, you will be brought to the Field Mapping page. Your phone number header will automatically map to Klaviyo's Phone Number property, which you can verify here.


If you uncheck the SMS Consent Timestamp box during the mapping process, you will be able to upload your list of contacts successfully, but won't be able to text these contacts until the SMS Consent Timestamp field has been added. Non-US numbers will not have a consent timestamp, regardless of whether or not this box is checked, as SMS sending is not currently available for non-US contacts.


Additionally, if you attempt to upload a list with phone numbers but without an SMS Consent Timestamp column, you will be prompted to update the consent status of these contacts before you finish importing the list. You may proceed through this process without adding a consent timestamp, but you will not be able to text these contacts.

Once you are satisfied with how the fields are mapped, click Import Review to proceed to the final stage of the import process.

Update Consent Status

If you do not have SMS Consent Timestamps in your CSV file, you will still be able to update the consent status. It is imperative that you only do this if you have, at some point, explicitly received consent from these contacts. Otherwise, you will be in violation of Klaviyo's Terms of Service and TCPA laws. If you are confident you have previously received consent, click Update SMS Consent.


Review the modal carefully. If you check I acknowledge that the profiles in this import have provided explicit SMS consent, you are verifying that you have previously obtained consent from these contacts, via another SMS platform or otherwise, and are willing to accept the legal implications of texting these contacts. 


Once you check this box, you may click Update SMS Consent once more. You will be brought back to the Field Mapping page, where you will see a row for SMS Consent Timestamp. For all contacts, this field will be populated with the timestamp at which you clicked to confirm Update SMS Consent. You will not be able to edit or update this field. If you decide that you don't want to proceed with updating the consent status of these contacts, you can click Cancel SMS Consent Update.

Review Your Import

On the final page of the import process, you will be able to review how many columns you are importing and how many you are skipping from the original CSV file, as well as if SMS consent has been updated (if applicable).


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