You didn't have to give them an ID because they knew exactly where the phone was going.

I had my first phone installed back when you had to walk down to the phone company office and sit at a desk and fill out a form. Then a week later, a guy showed up at your home and put the wires in.

When I had my second line installed, it was after the Bell breakup, but again they didn't ask for ID, but I had to give them a $50 deposit to be used against phone rental and per-minute service.