I'm just curious what they think anonymous actually means. When I look it up it says:
What you're likely seeing is a caller (usually a telemarketer) spoofing caller ID by placing the word "Anonymous" in the caller ID information that they manually enter in the system (aka spoofing). That's the caller ID information that gets displayed on your phone, etc. What anonomous call blocking really does is block any caller that has no caller ID information that is usually displayed as "private" on caller ID. When you turn on anonmous call block that's what you're doing -- is blocking the caller for which the caller ID information is blocked. Callers that have their ID blocked will get a recorded message that the party they have called does not accept anonymous calls and to unblock their caller ID by pressing *82 before they call.
Verizon could indeed explain the feature better and use better terms. But...
It's the caller ID spoofers who are breaking the law by inserting anonymous in their caller ID data.
You might look into nomorobo.com if you have FiOS Digital Voice. Some have reported it works well in blocking these bogus "anonymous" calls.