Before the Internet, all you could do with a person's phone number is call them. But now, with PeopleSearchNow.com (the ultimate free source of personal info--feel free to look up your own real phone number in it, assuming you're American) and with Google and the MULTIPLE social networks that virtually everyone between the ages of 20 and 45 has been on now--typically using the same username on most or all of them--you can find out way more in a matter of a few MINUTES than a 1980s private investigator ever could in a span of a month. I can look up your number on PeopleSearchNow and then, if I can't find YOU on Facebook, I'm confident I can find one of your relatives (several of whom will be listed on PeopleSearchNow), and get to you from there--meaning find your other online profiles, thanks to those Facebook friends who know you.

Phone companies didn’t leak phone numbers in the conventional sense of the word. I used it to try to draw a comparison. Phone numbers used to be printed in big books and you could usually look someone’s phone number up if you knew their name and rough location. That is, phone numbers were not considered to be particularly private information at all.

I think the comments I most agree with talk about the different security threats people face today with current usage of phones.