depends on what network they use, if it's a gsm network (which needs a sim card) you're SOL, if they use a cdma network that can operate on verizon's frequencies, you might be able to.
my guess from the seat of my pants, it won't work.
Of all the jokes that I want to make, and I wont say a word.
Mexico it will work in certain tourist parts, Cancun and so on. Coloumbia is a little different, and I have no idea about. You can go to VZW.com and go to business tab, which will show you the international coverage. You can expect a high bill for minutes while you travel.