When you travel abroad, you'll automatically receive an SMS to inform you about the roaming rates. You can choose whether or not to receive it. Here's how you proceed:
If you no longer want to receive these sms when you're roaming, here's what you do: send "ROAMING SMS STOP" to 19003, free of charge.
If you would like to be informed again by SMS when you're roaming, please send "ROAMING SMS OK" to 19003, free of charge.