What are international numbers for cingular? i got charged for 35.00 of...

...texting for it? One of my lines got charged an extra 35.00 for texting an international number? how can you tell what numbers are being charged? can someone tell me like area codes that are international? or places? Because i text alot and it takes forever to go through my text messages on cingualrs website!?
its 25cent for international an i do got unlimited. but i figured out what number it was it was a canada number .