Just replaced landline with a phone from cable provider. The line has caller ID blocked for all outgoing calls, but a call placed to someone with Vonage VoIP service resulted in my calling number being displayed on the receiving end. I had of course previously checked that caller ID blocking was set on my number by calling e.g. several cell phones that all displayed "private number". Is the VoIP company just ignoring the privacy flag and displaying the number as though caller ID had not been blocked?

NOTE: the number I called was not a toll-free number so ANI should not have been an issue.