I've read a lot about unlocking phones over the years. But this is the first time I have actually come up on a feature called "Sim Card Lock" where you enter a PIN to lock a particular Sim card. This feature is unlocked as long as I have my Sprint Sim in the phone. But as soon as I put in, like say, an AT&T Sim the Sim Lock feature turns on and locks. In other words, it has a checkmark where I have to enter a PIN to unlock it. Sorry to seem like a complete noob. But is this the same "sim unlock" many are trying to crack? There must be a PIN that has been coded in that locks down any foreign Sim. If so, it seems like it would be possible to figure it out. Every time I enter the incorrect PIN code, it always says I have "0 attempts left". So I can enter it as many times as I like without locking down my ATT Sim. Anyone know of a way to figure this out. Or is it even possible at all?