I'm trying to figure all of this out. I have a good understanding of the whole GSM 900/1800 worldwide and GSM 1900 North American standards. Also, I understand that Japan and South Korea do not use GSM. In addition to their separate native protocols, they both seem to support 3G.

Now, here are my questions: As far as I can tell, 3G is also known as UMTS and also known as WCDMA - am I right about this? Will a phone such as the Nokia 6651 which proports to support GSM 1900 and WCDMA 1900 work in Japan and South Korea, assuming that it has a SIM from a carrier that allows roaming in those countries (in my, case T-Mobile USA). I'm not concerned about a phone that works anywhere other than Japan and South Korea, as I already have a GSM 900/1800/1900 phone that works everywhere else.

What I'm trying to establish is that if I get something like the Nokia 6651 from T-Mobile (or elsewhere as long as it's unlocked), that I'll be able to roam in Japan and South Korea. Anyone know?