similar to some others but i have been travelling to us and really need mps, camara etc so i was hoping to get i phone a- not sure if 4g or 3gs and the difference between 4g and 4?
also i live in england so if i buy an unlocked i phone from ebay and put my simm in uk in it will it work?
also lastly sorry whats diff between unlocked and jailbroken?
thanks
there is no such thing as a 4G, there is the iPhone, iPhone 3G, iPhone 3GS, and iPhone 4, currently you can buy either the iPhone 3GS, or the iPhone 4.
Unlocked means the phone is not tied to any one network carrier, meaning any sim card can be used in it, but if you buy a phone on contract it will be locked to the network you got it from, and only a sim card from them will work in it.
Jailbraking is in a sense, hacking into the Operating System to open up extra features of the phone, using Apps that can alter the appearance and many other aspects of the Phone, you can unlock the iPhone by Jailbraking it, but you cannot Jailbrake the iPhone, by unlocking it.
if you buy an iPhone 3GS on ebay, then it would need to be unlocked, or locked to the same network as your current sim card, to be able to use it.
the iPhone 4 would be the same, apart from the fact that the iPhone 4 uses a micro sim card, which is smaller than a standard sim card, so you would need to find out from your network if they can change your sim to a microsim, but the iPhone 4 would still need to be either unlocked or locked to the same network as your sim.
lastly, depending on how old your sim is, you require a Data plan on your sim to use the features like maps than you mentioned, and also to use the iPhone in the US with a UK sim in will cost you a fortune!