It seemed as if the confusion over traveling internationally, or purchasing a GSM phone, had been sorted out: Get a quad-band GSM phone and you'll be set most anywhere in the world that has cellular coverage.
Enter HSDPA (for High speed data packet access). HSDPA otherwise referred to as UMTS, is the high-speed data access technology, often called 3G, most widely used by GSM carriers.
Problem is HSDPA works on different frequencies. So, you can buy a tri- and quad-band GMS phone, only to find it's high-speed data for browsing works only in one region. Now, you'd actually need a phone with ten bands (deca-band?) to cover voice and data everywhere.