Buying a BlackBerry off eBay - BlackBerryFAQ
If your carrier is TMo here in the US, you will need to purchase their International calling plan and International BlackBerry Data Plan.
There are other options as well (using a local SIM from the country you are in, getting a data plan there, etc.), but honestly, none of those options will easy nor cheap.
You really can't "remove" an IT Policy, you can replace it with a blank one. Be very careful buying a used BB off eBay for a trip coming up shortly.