I've never really thought of my phone number as private- they used to be published in phone directories, or via operator assistance. I suppose one may want to

I've never really thought of my phone number as private- they used to be published in phone directories, or via operator assistance. I suppose one may want to have a number, like Google Voice or similar service, that was 'unlisted' and you would only give it to a select group. The bigger concern for me is companies using the number to track me.