How Do I Know If My Sim Card Is Locked. This post has discussed 3 practical solutions to tell if your iPhone is unlocked or locked with simple steps. Insert a sim card of a different carrier and then turn on your smartphone.

Of course you will want an immediate solution. Though inconvenient its the most reliable way to determine the lock status of your phone. Here are the customer service phone numbers for all four major carriers.
However this method for checking your iPhones.
If you fail the three attempts your iPhone will ask for a PUK Code which you can only obtain by calling your carrier. Check out this support article on PUK codes for instructions on how to retrieve and use the PUK code. Makaela ATT Community Specialist. Each of our sim cards has their own unique PUK codes.

