Vonage Anonymous Call Block lets you easily stop those annoying anonymous calls. All calls marked from callers who have deliberately blocked their Caller ID will be sent to a system message indicating that you do not accept anonymous calls. The caller will be directed to hang up and try again with Caller ID unblocked. Callers whose Caller ID information is not available will not be blocked. Only Vonage gives you the control you want – without the cost.
Just dial *77 from your Vonage phone to turn on Anonymous Call Block, *87 to turn it off.