you can also enable your firewall to block all messages that are not from one of your contacts. options>security>firewall enable it and then check the box for the kind of message you want to block
I think, but I am not 100% sure, but you can block certain numbers using your carriers website. I know I can do this with Verizon. Of course, this is only for SMS.
If you have alltel, send a text message to 8888 then in the message field put a "b" then a space then the number. You will get a reply saying that is blocked. To unblock send a msg to the same number 8888 type "u" space then the number. To list the blocks you have send a msg to 8888 with the letter "L" in the msg field and it will reply with the info.
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