iPhone is a quad-band GSM phone that will work in most parts of the world, but it is locked for use with AT&T only. You can roam internationally, paying AT&T's international calling rates, but you cannot buy a pre-paid SIM from a local vendor for more affordable phone use.

Not all areas may support the EDGE data network. According to AT&T's International Travel Guide, most of Europe has iPhone EDGE coverage, as well as Russia and China. Visit the web site to get details on coverage within each country; even supported countries may have areas of spotty coverage or no coverage.