Best method to prevent incoming messages/calls is to ask your carrier to block the number at their end. You may block it yourself by using firewall filtering on the device but you will still be charged for messages and calls because they're still routed to you by your carrier.
__________________ Treat your password like your toothbrush. Don't let anybody else use it, and get a new one every six months. Clifford Stoll
ATT Offers smart limits. $4.99 a month you can block up to 15 numbers all text and emails attached to any of those numbers. BEST $4.99 a month I am spending!!!!!!!!!!!!!
There is also a application on mobihand.com called CallBlocker that allows you to block calls and specific numbers...It may say that its not compatiable with specific models, but i have a 8320, which it's not compatiable with, but I tested it and the private/unkown calls didn't come through or even go to voicemail/just got a message about the call not being completed...It really works! I love it!