It's worth a call to your nearest dealer, they provided the radio code for me (I mean who really would steal and then want to reactivate a CDR220 from a 99?!
).
Turn on the radio and hold down the "tp" button for 5 seconds then you should see "Becker" turn the tuner knob and you should see a serial number. This is the number you need in order to retrieve the radio code from the dealer.