I found this off another site. I have tested this withy my D807 and it works.
1. If you have changed your phone password, change your password back to the default 8 zeros (00000000).
1a. NOTE (Modification here by my experience): Goto SETTINGS, SECURITY, then SIM LOCK and disable this before proceeding.
2. Put a SIM card that is from a network other than the one your phone is locked to (I used a TMOBILE card from my buddy Darin)
3. When Incorrect SIM (I got invalid card and there was a sim card graphic spinning) error comes up, type *#9998*3323#.
4. White screen will appear with an exit option. Press the right softkey. (I ended up pushing the down key to get a menu)
5. From the menu that appears, select the Malloc Fail option. This will reboot the phone and the normal service screens will appear.
6. Type *0141# and then press the green call key. "Personalization" or "Personalized" will appear.
7. Turn off your phone and put the original SIM back in.
8. Turn on your phone. You will receive a prompt to enter a password.
9. Type 8 zeros (00000000) (This is because the SIM LOCK Mentioned earlier gets switched back on)
10. Completed. You have now unlocked your phone.
Easy as pie. Now you have an UNLOCKED Samsung D807 =) worked on my brand new 2 day old Samsung D807 phone.
Oh also guys I called Cingular (on hold for 1 hour with these losers) and they told me there is no way to SAVE phonebook contacts from the phone to your sim card. Now this really pisses me off. So I did some searching and found out that with the studio software from samsung you are able to edit and move contacts from your phone to the sim and back. Or copy from the phone and put them on the sim card. Just thought you all should know as there is no menu option on the phone.