I don't know for sure, but I doubt these phones would work abroad. We use CDMA here, and one needs GSM or other systems for abroad. Even if sold to another CDMA country, who would the carrier be (these phones have pre-paid minutes, right?).
We use both GSM (Cingular, T-Mobile) and CDMA (Sprint, Verizon) here. The $20 Walmart phones are GSM. Most countries use GSM. The phones are "unlocked" so they can be used on any carrier with the right sim card. You would have to buy a new card for the minutes in whatever country you wished to use it in.
There was a guy that was in Iraq that posted a pic a few days ago of a wired Nokia that didn't go off.