Korean Iphone 4 to Sprint?

[sick an twsd]

I've been stationed over in korea for 2 years now and i was wondering if it's possible to bring my Iphone 4 back to the U.S and hook it back up to my Sprint account

a little about the Phone
(GSM - A1332)
(Model - MC603KH)
Version 5.1.1 (9B206)

any help would be greatly appreciated but from what i've been reading it seems like the Sprint Iphones are all CDMA and the older iphones are not GSM/CDMA like the Iphone 4S.