You get the Service Books from the carrier. If you don't have an active BlackBerry Data Plan, then you won't have them and BlackBerry Data features will not work even over WiFi.
You might want to consider looking into Verizon's Global Plans if data will be important to you.
International Services
Alternately, if you know people who are currently using BlackBerry Data in Thailand, you might ask them from what carrier they obtained service.