Woulb be nice if Sprint offered some phones with an empty sim card slot. That way international customers could use the phone in any country by just buying an inexpensive sim card. This would bring a lot more customers. They could still seal the phones like they do to prevent "hacking", but have a sim switch to use the available slot for international travelers. I been a customer of Sprint for over 10 years and now that I travel a lot overseas. I am renting or buying phones to use there because it is cheaper then using my Sprint phone internationally. Please get into the next generation soon... Thanks!
All of Sprint's CDMA/GSM worldphones have unlocked SIM card slots. They come with a Sprint international SIM but you can simply switch it out for a loacl SIM card if you want.
Then your choices are to go with a GSM carrier in the U.S. like AT&T or T-mobile, or to use a local GSM phone and SIM when overseas.
This is one of the downsides to half of the world using CDMA and another half using GSM, along with iDEN mixed in for good measure.