I am currently with Orange and am going to upgrade to the Iphone 4. They don't have the 16GB available just now however the carphone warehouse does, I am a bit confused though, If I choose the upgrade option on the carphone warehouse website and fill in all of my details will orange cancel the contract on my current phone and just change it to having the Iphone or will I have to get my new phone and cancel the old contract myself 
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