In detail, it worked like this: I called a technician in the appropriate central office. Believing I was a repair tech in the field, he clipped onto the manager’s line using a lineman’s handset and dialed the digits I gave him, effectively call-forwarding the manager’s phone to a phone company "loop-around" circuit. A loop-around is a special circuit that has two numbers associated with it. When two parties call into the loop-around, by dialing the respective numbers, they are magically joined together as if they called each other.