Are you going abroad and want to be able to put a local SIM card in your Galaxy S3? Or do you want to switch to a different provider but keep the same phone? Then you may have to unlock your phone first. Fortunately, if your provider doesn't want to do it for you, there are other methods. Read this article to find out how to remove the SIM lock from your Galaxy S3.
Method 1 of 3: Unlocking by your provider
Step 1. Contact your provider and request an "unlock code"
You can often only request this without costs if your contract has been running for more than a year. If you request it sooner, there will probably be a fee. Call your provider for more information, and if it's too expensive, follow another method from this article.
Explain to your provider that you are going on a trip and you want to be able to put a local SIM card in your phone, maybe they will give you an unlock code sooner
Step 2. Insert the new SIM card into your phone
Step 3. Turn on the phone
Now you will be asked for the unlock code.
Step 4. Enter the unlock code
Now your phone will start searching for the network of the new provider. If you are unable to connect, please contact your new provider.
Method 2 of 3: Unlock without your provider's permission
Step 1. Update your phone
You must have at least Android 4.1.1 installed on your phone to use this method. Check which version you currently have by looking in "Settings". Scroll down and select "About device". Next to "Android version" you will find the version number.
To update the phone, go to Settings > About device > Software update. Select "Check for updates". Now the phone will try to update over the network
Step #2. Open the calling screen
You have to enter a code with the number keys to open the service menu. Enter the following code: *#197328640#.
Step 3. Select  UMTS
Once you have entered the code, the phone will automatically open the "Service mode" menu. Here you select  UMTS.
If you select the wrong option, press your phone's menu button and select "Back"
Step 4. Enter the "Debug" menu
Select  DEBUG SCREEN. Then select  PHONE CONTROL. Here you select  NETWORK LOCK.
Step 5. Select  Perso SHA256 Off
Wait 30 seconds after entering this choice. Press the menu button and select "Back". Select  NW Lock NV Data INITIALLIZ.
Step 6. Wait and reboot
After you have selected the last choice, wait a minute, then restart the phone. No confirmation appears as to whether or not the process was successful.
Step 7. Insert the new SIM card into the phone
If you don't have to enter an unlock code now, it worked. Check if your new SIM card has a network connection.
Method 3 of 3: Unlocking through a website
Step 1. Find your phone's IMEI number by typing *#06#
A screen with the number will now appear. Write this number down, you will need it later.
Step 2. Find a SIM lock service
There are many websites where you can have your phone unlocked for a fee. Read reviews first, always choose a service with many satisfied customers. You will need to provide your phone's IMEI number.
These services operate in the gray area between legal and illegal. It is not entirely clear whether unlocking by third parties is legal
Step 3. Wait until you receive an unlock code
Sometimes it takes a few hours, sometimes a few days. You can receive the code by text message, by e-mail or by telephone.
Step 4. Insert your new SIM card into your phone
Enter the new unlock code. Check if you have coverage.