[phen0m]

Can an unlocked 4s be used on the Sprint network? ie if I buy a factory unlocked 4s, can I activate that on CDMA or GSM?

[alm]

If you buy the unlocked phone from the apple store, it is a GSM phone only. It can't be used on the Sprint network as Sprint is CDMA. In the US it can be used on the AT&T or T-mobile network. Currently you will only get 2G data speeds on T-mobile until they complete their refarming project. If the phone requires a SIM card then it is more than likely a GSM phone.