I have read a lot of different discussions about unlocking the XPRT.. and found a website offering to do it for a price... BUT. I just called Sprint Technical support, AND the Sprint International services number and both told me the XPRT is unlocked.
So to answer your question (and mine, haha) you can swap out the Sprint SIM card for a local carrier SIM card and avoid expensive voice and data rates. Thank goodness, lol..
I am in currently in the Middle East and confirmed that local SIM works on the XPRT. It is unlocked. Works great.