Before the Internet (at least, Internet available to people outside a few institutions), caller-id was either not available at all or an extra-cost service you

Before the Internet (at least, Internet available to people outside a few institutions), caller-id was either not available at all or an extra-cost service you had to pay for. So the normal case for a ringing phone was that you had no idea who was calling or any way to get the number. Those capabilities came later. You'd look up someones phone number in the white pages and anonymously called them. Which of course was a source of much entertainment for us kids of the 70s and 80s. Now, of course, the phone company knew both numbers, so there wasn't any privacy in that sense.