Using another countries carrier with a US Sprint TP2

[zztoolzz]

I know the TP2 is a world phone but my question is this. Would it be possibe to actually use the TP2 with a carrier from another country? I know you can unlock it and use it with other carriers like Verizon, At&t, and T-Mobile but I haven't really seen anything said about carriers in other countries. I also know it works with the pre-paid sims overseas also. I'm asking cause I'm selling a new TP2 and the person says they want to give it to a family member overseas. I actually don't know which country though. Any imput would be much appreciated.

TIA