Hi Rock thrower,
Don't mean to cut mainframe's grass.
Quad banded phones will work on the following frequencies, WCDMA 850/ UMTS 2100, GSM 900/1800/1900. tri banded phones generally work on GSM 900/ 1800/ 1900. The 3G network is the UMTS 2100 and nextG is WCDMA 850. As far as world roaming is concerned you need to check that the handset you have or intend to get will operate in the country you intend on using it in. some Asian countries in particular do not use a frequency that we have here in Oz. I would suggest looking at your carriers website or the maker of the hanset's for further info.
Cheers.
