How To Unlock My At&t Sim Card. After activating SIM lock you must enter the PIN code if you move the SIM card to another device. Select or type in the brand of your device.

The first place where you should look for the PUK code of your SIM card is that plastic card that we mentioned before where your SIM card came from. Select Manage my device. Searching the CM10 nightlies thread it seems that the builds where that bug was still around back in the JulyAugust builds.
Not an ATT customer.
However many people that buy SIM cards just tend to discard that plastic losing the PIN and PUK code. 100 Guaranteed to P. Under See device options select Get your PIN unlock key PUK. When enabling SIM lock your device prompts you to enter a PIN code.

