Sprint iPhone 4S use in China?

I have a iPhone 4S currently under contract with Sprint. I'm moving to China and would like to use the iPhone under another carrier like China Mobile or China Unicom. My understanding is if I cancel my contract (fees may apply), jailbreak the phone, then unlock it I can use it with another carrier in China. Is this correct? Also, do I need to have the new China SIM card to perform the unlock process, or can I unlock it in the US then take it to China?

I don't think so. I personally don't have Sprint iPhone, but most Sprint phones do not use SIM cards. The information is programmed into the phone itself. So not sure if you can buy a SIM in China and use that on your iPhone (unless there's a slot for it).In any case, you will need to jailbreak it first.

My suggestion is to take the phone to China. Take it to a cell phone store (ALL OVER THE PLACE). And ask them to do everything for you, including SIM replacement, jailbreaking, etc.

Just because the iPhone 4S works in the USA, does not mean that it will work in China. You will soon discover that the wave carriers are completely different. Your iPhone will have to have a tri-band capability to work in China. Simply buying a China Mobile or China Telecom card will not work. The electronics are completely different.

If you insist on using a USA bought phone in China, make sure that it has Tri-band capability.

It will work in Hong Kong, but the fees and rates will blow your budget out of the water. Just go buy a local iPhone when you come to China. They are cheap here. The Chinese don't have to pay all the importation fees and costs added on by the USA government.

That is incorrect. They DO have to pay import taxes because iPhones are Apple and regardless of where they're made, they're from the USA.