I forgot my unlock code for my samsung blackjack 2

To unlock your BlackJack cell phone, will need to Call AT&T and request a Network Control Key (its free). They may ask you for the phones IMEI code.

Alternately, you can do a web search for a Cellphone Unlocking Service (they charge about $20).

Additional info:
http://forums.wireless.att.com/cng/board/message?board.id=samsung&thread.id=55160
http://www.corynielsen.com/modifications-and-hacks/unlocking-the-blackjack-sim-card
http://www.ehow.com/how_4812573_unlock-samsung-blackjack-cell-phone.html

Hello Friend,
Here is the procedure:

1. First you’ll need to get your Network Control Key. The Network Control Key is a 8 digits unlock code. There are two paths to get your NCK. You can either call AT&T or ask for it. You may have to ask them to put you through to their tech department. If you’ve never signed up for AT&T’s Service they may not give the code because your not a customer. The other way to get the code is to contact a cell phone unlocking service. They usually charge around $20 to get this code for you.
2. Once you get the Network Control Key power off the phone.
3. Remove the SIM card.
4. Power on the phone back on.
5. Enter #7465625*638*
6. Enter Network Control Key.
7. Press “OK” Soft key, not the Send or OK hard key.
8. Power off the phone.
9. Reinsert the new SIM card.

Best Regards,