I jst got an iphone yesterday. I wanted to get the 16gb white version but they didn't have any in stock and i'd been trying to get one for ages so I finally caved and bought the 8gb. I was wondering....now that I have activated my O2 sim card, if I were to sell my iphone and buy a 16gb one from ebay would it work with my sim card or does the sim only work with the phone that it has been activated with? I really want the white version! Also, I asked the guy in the shop when I was buying it if I cud upgrade to the 16gb white version when it came into stock and just pay the difference but he said I cudn't! Is this true? I thought I would have been able to because people who owned the iphone 2g could upgrade to the 3g version even though they hadn't completed their 18 month contract and so didn't have an upgrade. I thought it would have been the same as this. By the way, I bought it in Ireland if that helps. Cheers!