How to unlock the Blackberry Curve 8300 (should also work on 8310, 8320 & 8330)
Step 1: Intro to Unlocking
When you unlock a cell phone you allow it to work on all GSM carriers. This works with most GSM cell phones. For example if you have a phone that only works with AT&T you can unlock it and it will work with T-Mobile or vice versa.
To unlock your phone you will need an unlock code. To get this open your phone and look behind the battery. You will see an "IMEI" number. Go to a site which has unlock codes such as cellification.com give them your phone model and IMEI number and they will produce this code for you.
Step 2: Navigating the Menu
Turn off your wireless connection, then hit menu -> Settings -> Options -> Advanced then Select “Sim card”
Step 3: Secret Codes, Hidden Menus and the Secret to the Universe
Hold down the CAP key while typing MEPD (the letters will not appear) If you did this correctly the personalization menu will magically open.
Step 4: More Hidden Codes
Under personalization it will say Network: Active. This means your phone is locked. Hold the CAP key again and type MEP2 (Instead of CAP, use ALT for the 2)
It will ask you for your unlock code and give you 10 attempts to correctly enter it. You can get this unlock code from sites such as Cellification.com
Step 5: Congratulations!
After you enter the code you will notice under the personalization menu that it will say Network: Disabled.
Congratulations! Your Blackberry is unlocked!