If you have a Samsung Galaxy S3, S4, Note 2, Note 3 or your Android version is Android 4.4 (KITKAT)
All SAMSUNG devices manufactured after the date of JULY 2013 and Samsung devices running on Android version is Android 4.4 (KITKAT) are subject to REGION LOCKING
If your phone has been used previously with the original carrier, this will not apply to you. However, if your device is BRAND NEW, you must activate it with the original carrier.
If your Samsung device becomes Region locked, you will not be able to fully factory Unlock your Samsung devices so it can be used internationally. Even the correct code will not work anymore.
In order for your Samsung device NOT to be region locked, you MUST activate (FIRST USE) your S3, S4, NOTE 2, NOTE 3 with your ORIGINAL carrier at least ONCE to take your region lock OFF. After your Region lock is off, you can Sim Unlock your device via Unlock Code.
*All Canadian Carriers are NOT subject to Region Locking
*All USA and European Carriers ARE subject to Region Locking
Region lock is removed automatically after you activate your device with its original carrier. Make some call's before sim unlock.
(Insert an active original sim card into the device and make a few calls to activate the phone and bypass the region lock. Once you've activated the phone, you can input the unlock code.)