I also believe that if your sim card is associated with another carrier you may have to ask them to unlock it and they may or may not depending on if you owe them any money on a phone or service. Q Link however provides their own SIM card and sends to you. At least the one that fits the phone that they send. There's only one drawback to the phone they send and mine doesn't keep a charge for more than a couple hours even without using it. But I do think that Sam does fit in another Android phone but I have to get them to let me know if my phone's compatible with their service.

I looked online for a answer to your question. Here's what i got.

To unlock your SIM Card, reset the PIN by entering your SIM Card's unique PUK (PIN Unlock Key). Note: Entering an incorrect PUK (PIN Unlock Key) 10 times will permanently lock your SIM Card. If the SIM Card becomes permanently locked, you will need to swap it for a new SIM Card.