Bell's Guide on How to Use a Rotary Dial Telephone

Long about 1970, I was in the 3rd grade, and The Bell System came by my school with a setup to teach the material in this pamphlet.

There was a box that stayed in the hall and two rotary phones that ended up in 2 class rooms. The Bell System person showed everyone how to answer (try to pick up within 4 rings) and how to call (let it ring no more than 10 times). Then we got to practice. Pick up one phone, the other phone started ringing! You could pick up and talk to someone in the other classroom! It was great!

As an adult I worked a spell at a baby bell, before cell phones killed them. It turns out that the whole Bell System demo was self serving. Each central office has a "ringer", a machine that generates 60Hz AC, which is what rings old land line phones A ringer has a fixed capacity, it can only cause so many land lines to ring. If teenagers are letting phones ring too long, the Bell System had to buy more ringers