I have longed for an iphone ever since they were invented! I have finally decided to buy one. I have purchased an unlocked one via ebay so that I can just use my PAYG sim card. It is a 32gb 3GS. BUT, and this is a big but, have I made a mistake? Would I have been better getting it through a phone provider on some sort of plan? Will using it with my PAYG sim mean that a lot of the features I have on the 3GS will not work? For example, I recently purchased the NDrive app for UK and Ireland. I guess that will not work unless I am in a wi-fi zone, and that is no good on a motorway anyway! Big error I think!! Can anyone help? Also, if I do go into a phone provider and ask to be put on a plan, how do I know when I've used up all the free data allowance and move into extra charges time? I am totally green in this area as I've never had a phone plan, always gone for PAYG and it has only just dawned on me that with such a great phone actually I may have made a big mistake. Any advice?