There are two categories of credits, “standard messaging credits” and “international credits”. Depending upon which country your short code is housed in, and to which country you are sending messages, you may need to use one or the other.

• If you have a U.S. short code and send to phone numbers in any other country including Canada and Puerto Rico, you need “international credits”.
• If you have a Canadian short code, you can use “standard messaging credits” to send to Canadian numbers, but need “international credits” to send to the U.S.