I sold my old 3G Iphone on eBay a couple of weeks ago. The buyer has sent me a message saying this: "hiiii i have prchase from you IPHONE 3G 8GB and just yesterday i receaved it from DHL but i realise when i switch on it appear on DFU mode.... can i know the resons and why u didnt put the softwere??" Before I sent the phone I erased all my content off the phone. When you turn the phone on, it is asking for the connect to iTunes. My question is, what is DFU mode?