Exactly. (Also, Alltel uses CDMA.)
The frequencies are different, and when CDMA1900 (what Sprint uses) or CDMA850 are referred to, it's referring to the general area that both receive and transmit frequencies are in, and the transmit frequency range is right after the receive range.
This has the receive and transmit frequencies at very different frequencies.
However, it does use the same protocol (with one exception - if you get one of the European models that has a GSM radio for terrestrial calls, it uses GSM authentication, but the rest of the call is CDMA.) Oh, and from what I've heard, they're going to be upgrading their network to support EvDO soon, even. Right now, I believe they're using QNC.
But, that's when it works - a bunch of their satellites are broken, and the odds of completing a call aren't that great.
But, this is an off-topic tangent, let's go back to a real international use discussion, none of this satphone talk.