Accepted Phone Number Formats for SMS in Klaviyo

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Klaviyo currently accepts several different types of phone number formats for SMS marketing. In this article, you will learn about these accepted formats and tips for importing phone numbers into Klaviyo. 

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)
  • First and last names
  • Consent
  • Phone number
  • Country 
  • 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

When there is a column for Country, you can either include or not include the country code for the phone number; it will work either way. The examples below show both options. 

Without the Country Code
With the 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 while you cannot currently send SMS messages to any country other than the United States, you can begin collecting consent from those in other areas. However, SMS for other countries is on our roadmap, so stay tuned!


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

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