Apple iPhone 3G - 16 GB - White (O2) Smartphone ?

This is a used iphone 3G (16GB) in excellent condition. It has always been in a leather case and had a screen protector. The rear case has small hairline crack (see photo) due to a design flaw in this model. It is in perfect working order and has hardly been used during its 3 year life (it was owned by my mum who used it for rare texts and calls). This phone is currently locked to o2 network but it can be unlocked. It comes with the original Apple box and all accessories (including new headphones, usb lead, adapter plug, manuals). This is a fantastic phone in great condition. Any questions will be answered quickly. Thanks!