The Texting platform is currently available for domestic communication only. If you are using 1:1 Texting or sending a Campaign, you cannot send a text to an international number. 

For Campaigns, when you are uploading a contact list and you include an international number, the number will not import into the contact list. Once the contact list has been uploaded, you will be given a CSV file of any errors. For more information on fixing Contact List errors, review the Creating Campaigns Contact Lists article.