SMS to Puerto Rico:error only US Numbers

There are notes in CC that say SMS is only available to US numbers and Puerto Rico at this time. 

We can't enter the 10 digit phone numbers we have for customers in Puerto Rico that have agreed for us to send them texts. 

We have updated the profiles, but it give error "invalid US number."

Is there a setting or other format to use when sending the SMS invite to a Puerto Rico phone number?