The 8830 can be used on GSM 900MHz, both for voice and data. It was designed as one of the first "world phones" but for roaming outside North America only. The idea was to use the Verizon international data roaming plan with the SIM card Verizon provides. But folks have used it unlocked to get their email on BIS on just the GSM side.
Check out
www.horizonwirelessonline.com to get a legit unlock code.