You can use your BlackBerry’s firewall to block SMS, MMS, PIN, and/or BlackBerry Internet Service messages. This can be useful in avoiding spam or preventing you from ringing up extra charges.
1. Go to the Home Screen on your Device.
2. Press the menu key to show all your applications.
3. Select Options.
3. Scroll down and select Security Options.
4. Select Firewall.
5. Set the Status to Enabled.
6. Under Block Incoming Messages, select the type(s) you wish to block. (choices are SMS, MMS, PIN, and BlackBerry Internet Service).
7. Press the menu key and select Save.