This ought to be an easy answer, but I can't seem to find the answer anywhere. How does one make a local mobile call overseas? Does it vary from country to country?

ATT says that my phone will act like a local mobile overseas and "you should find out how to make a local wireless call when you arrive." So, how do you make a local call overseas? It can't be that hard can it?

(I only use my cell for emergencies like reservations for dinner or calling the rental car agency when I got a flat tire. I have a Mobol phone which works fine for me in Europe. I just haven't been able to use my Treo overseas for anything other than calling the US. Yes, I've signed up for international roaming. I get a network fine, I just can't figure out what numbers I have to dial to call someone locally.)