I want to be able to unlock (for use on any network) a few Sony Ericsson K800i mobile phones using the USB cables supplied with the phones and downloadable (ideally free) software. What software do I need and where can I find a 'dummies' guide to unlocking the phone using that software? Specifically it's a Sony Ericsson K800i (with an EPROM CID of 53 if that makes a difference). Ideally I'd like to do this for free but am prepared to pay a small amount for it; however, as the local market stall can probably unlock it for me for under £10 it's not worth paying anything over that!