1. Would you share the error message with us? Do you have any settings for the APN, located at Options, Advanced, TCP? What is there? If nothing, not knowing your carrier, I can't say what to put, but look here to determine your carrier's APN settings: BlackBerry Internet - MSN/chat/web/telnet/TCPIP - No BES!
2. Are ALL calls seen as UNKNOWN? What are your settings under Phone Dialer, Options, Smart Dialing? Should be Country Code "+1" and Area Code can be blank.
3. Your BB does not have a spam filter. Filter out the spam on your POP account at the email server, best way. There are other tricks and routes to take, but this is the best way to start.