Carriers may be more likely to unlock your phone if you explain to them that you are traveling abroad soon, and need to buy a SIM card at your destination for local service. If your provider does not supply the code, try one of the other methods in this guide.
Make sure to write the code down, because it cannot be copied to your phone’s clipboard. You can also find the IMEI number printed on a sticker underneath the battery of the S3. However is not recommended to take it from the box or underneath the phone’s battery as it might be different and your unlock code will not work.
To update your phone, open the Settings and then scroll down to About Device. In the next menu, select System Updates and then Check for Updates. Your phone will attempt to update over the network automatically. Perform the network update over a wireless network, since your new SIM doesn’t have any connectivity yet.
This method is not guaranteed to work with all versions of the S3, but you will do no damage in trying.
