Accepted Phone Number Formats for SMS in Klaviyo

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Learn which phone number formats Klaviyo accepts when importing phone numbers for SMS marketing. 

Accepted Phone Number Formats

You can use several different formats for phone numbers with Klaviyo. Below is a chart listing the accepted phone number formats and examples. Note that the country code is included in the examples, as Klaviyo must know the country in order to properly apply consent. 

Format Examples
E.164 +12345678900
+12 345 678 900
RFC3966  tel: 12345678900
E.123 national notation   (1234) 567 8900
E.123 international notation  +12 345 678 900
 +1 234 567 8900

The RFC3966 format comprises the prefix “tel:” followed by numbers. The numbers themselves do not need to be in a certain format.

Alphanumeric sender IDs are not accepted, but you will get one free with your SMS plan. 

Importing Phone Numbers

In order for consent to be applied to a phone number, we recommend including the following columns:

  • Email (if known)
  • Phone number (required)
  • Country
  • First and last names
  • Timestamp

This way, the file contains all the necessary and helpful information. Not only will consent be applied properly, but you'll avoid creating duplicate profiles.

For more details, read Upload a List of SMS Contacts

Including a Country Code

We strongly recommend including a column for the country; however, including the country code also works. To include the country code, use an apostrophe before the plus sign (e.g., '+1).

With the Country Column
Sample CSV file for importing SMS consent into Klaviyo when there’s a country column
With the Country Code 
Sample CSV file for importing SMS consent into Klaviyo when there’s a country code

In other contexts, such as API calls, Klaviyo can also infer the country code based on profile information, such as a profile’s location, shipping, or billing address country.

If you are collecting consent through Klaviyo and have customers in multiple countries, the best option is to create individual signup forms that target customers by location and then change the default country code based on that location. Note that Klaviyo SMS is available only in certain countries

Klaviyo signup form builder showing a phone number input field in a form with an image of a phone on the right

How Klaviyo Handles Symbols and Spaces

Klaviyo can also handle certain typos and common symbols. For instance, if a phone number contains a symbol, extra space, or letter, Klaviyo will remove this when a phone number is added to a profile. The following will all be corrected to the E.164 format as +12345678900:

  • +12/345(678)*900
  • +12()*- 345678900
  • abcde()*()++12 345 678 900
  • +1-2-3-4-5-6-7-8-9-0-0

Additional Resources


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