am I going to pay an extra fee (other than the $30 that the plan costs) for sending messages(from Orlando, FL) to another blackberry in another COUNTRY using the BLACKBERRY MESSENGER?

I am confused because at cingular they told me that they charge that as INTERNATIONAL data, and it is not included on the plan.

Thank you
P.S: I am not going to use my BB in another country... I want to use it to send messages from the U.S using the BBMessenger to other countries...