I also owned an 8830, but didn't travel outside the country during the short time I used it before switching to the 8330. My understanding of its capabilities, with regard to data, was that it has a sim slot so that when one does leave the country you are able to purchase a sim card abroad and use whichever features you pay for using the foreign sim. This obviously would involve having to use a different phone number as well. I'll see if I can dig up some of the literature I used when making the decision to purchase this phone......which I still own btw, for when I do travel.

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Edit:
If you go HERE you will see that they have next to no specific information on data roaming and most FAQs end with you having to call a special CS number to get info. This is because Sprint is very weak in the international dept, except in Australia, Mexico and a small handful of countries.

Basically Sprint will place the responsibility on you to figure all of that out by purchasing third party sim cards, etc. Honestly, and I mean this with all due respect, it sounds like a case of you not doing enough (or the right) research on the matter prior to purchase. I can give you the number to SPRINT/NEXTEL Executive Services so you don't have to deal with standard CS as you try to resolve this matter if you pm me.