Almost all the sim lock check tools and websites right now are not giving an accurate reading for the iphone 5 becuase they have not updated their servers, and most are charging to get an accurate reading. You might have an unlocked iPhone 5 that will say its locked, or will say unknown, or will say server down.

Their is one that is accurate and it has been implemented into a mobile app, it is only for att iphones. You need to get your hands on an android phone and get the FREE app from the android market google play store.

Search for the app called "iPhone Unlock" by Skyline Designs. When you open up the app their will be a button on the lower middle of the screen that will say sim lock status, click on it and thats the sim lock checker free to use.

Anyone can verify this, if you have a used phone its always good to check its status or if you are about to buy one or had it unlocked, you can verify it.