To use internet and features such as FB app, email push, Blackberry maps, google maps, alot of other applications, Blackberry Messenger; you need a Blackberry data plan.
Call Orange once you have the device unlocked and they should be able to help you.

As a side note, has your unlce upgraded his BB to a new one, or abandoned BB altogether?
If the latter, and he used blackberry features, get him to call t-mobile and ask that the BIS account be deleted.

If he didn't use blackberry features, it shouldn't be a problem.