I have the 8830 WE with Verizon. Is there a way to prevent calls and text messages from unidentified calllers? How about from specific numbers?

For specific numbers, you can always have Verizon block them. As far as unidentified callers, you can get the program Blacklist/Whitelist and I think you can set it up for that

If you go to Options-Security-Firewal, you can set up blocks for SMS, MMS, PIN, BIS, and BES email. You can configure "whitelists" using your address book and/or configuring specific addresses.

This works on the AT&T 8820. Hopefully Verizon weren't ***s and left it enabled as on option for you.