How to enter my Unlock Code on Cingular BlackJack ?

Insert disallowed simcard (a simcard that the phone does not usaully accept) and enter unlock codes when prompted

NOTE: If you are unable to connect to service provider or unable to make out going calls or recieve messages, this has nothing to do with your phone being locked or not, you need to force the BlackJack to change to GSM mode, this can be done as follows:

Power on your Phone

1. Enter *#1546792*#
2. Select Option 3 Network & Call Settings
3. Select option 5 Network Mode
4. Select GSM

This should resolve your problem.