Your phone is on these bands:
CDMA2000 1X 1900/800 / AMPS 800
Many of the American carriers "hardwire" the information normally contained in the SIM cards into the phone. Verizon does it, and I guess from the previous post, so too does Sprint. Essentially it means you don't have a SIM card (the easiest way to switch carriers) and thus, your phone is hard locked to Sprint (unbreakable). Not entirely sure, but that's what it sounds like.
Your phone is a 3G phone from Sprint. I'm not sure, but in talking with the the 3G people here there are all sorts of problems using 3G phones from other places (and vice versa). I was told that if I bought a 3G phone here in HK, I would not be able to use it on the 3G networks in London (that was 2 months ago, things may have changed, may have not).
There are CDMA cards I've seen here, but if your phone is hard set to Sprint, I think you are out of luck.