All other ford radio code websites charge anything from £5 to £10 to generate an unlock code for Ford radios. Ford charges £20 I believe. The code is needed if you disconnect the radio, or sometimes if you disconnect the battery.
It works with M and V series serial numbers found in Focus's, Fiestas, and Transits (probably a few other models too).
This site will generate them for free and works instantly without any sign up.