If you have just bought a new Blackberry Curve and want to switch service providers, you must unlock your phone, making it compatible with SIM cards from other phone networks. You don't need to bring your phone to your service provider. You can unlock the Blackberry yourself by changing its settings.
Turn on your phone and find the "Menu" control button by navigating with the large silver button below the screen.
Go to "Options" and scroll up to "Advanced Options."
Scroll down to highlight the words "SIM Card" and click.
Use the keypad and type in the letters M, E, P and D. The screen will now show 5 different lines from which to choose. These are SIM, Network, Network Subset, Service Provider and Corporate.
Use the keypad again and type M, E, P and the number 2. This should give you your MEP number. Write it down. Go through these steps again and this time enter the number manually using your keypad. Press OK after and your phone should be unlocked.
If you are leaving the country, your cell carrier will unlock the phone for you for free.