Do mobile phones purchased in a country work in another country?

Question

as buying a phone in the usa for a user outside the country, for example..

Answer 1

A Verizon phone will not work in other countries. Nor a Sprint phone.
If you buy a T-mobile phone, a Cingular phone, or an Alltel phone, and then get it unlocked, then it will work in other countrys. T-mobile has the best unlocking policys. Go into a store and talk to a representative.
Make SURE you have a "quad-band" phone. That is: GSM 850/900/1800/1900
Many phone won't have the 850 band, and then will pick up very little in other countries. My V330 working in Israel, Jordan, Lebanon, and Syria. Goodluck.
(Make SURE you get it unlocked, otherwise you won't be able to put another SIM in it)

Answer 2

If you buy it in US, be sure to get it unlocked. It would have to be a GSM phone byt he way, because few countries use CDMA. If you don't get it unlocked chances are that he will not be able to use it. Google the words "Unlock a Cell phone" for more assistance.