This strategy allows anyone to use the unlocked iPhone 3G with any cellphone carrier.
According to the Apple website, iPhone 3G purchased at the Apple Online Store can be activated with any wireless carrier. Simply insert the SIM from your current phone into iPhone 3G and connect to iTunes 8 to complete activation.
8GB : HK$ 5,400
16GB : HK$ 6,200
Check it out http://store.apple.com/hk