If you stick with an 900/1800/1900 GSM (commonly called a Tri-band) phone, and you'll be happy pretty much everywhere except for Japan, South Korea, and parts of the Carribean.

More info on how cell phones work here: http://electronics.howstuffworks.com/cell-phone.htm

Compatibility on GSM network coverage here: http://www.gsmworld.com/index.shtml

[This message has been edited by skofarrell (edited 09-29-2003).]