International travel

I will be traveling out of the country for a few days. I just spoke to someone at att about my service plan/charges. She told me she couldn't help me and tried to transfer me to international. She said that there wasn't a transfer option. So she gave me the international phone number, and the message said I couldn't access that number from the US.

Can you please let me know what I need to do so that I'm not charged a lot to use my phone I internationally? Can you make that adjustment to my account? My travel dates are 1/22-1/27.

Thank you.