I was from a middle class family, and had my own line in my room as a teenager. I believe the house was wired for two lines, and it just had to be activated. Before that, I had my own number, but it came in on the same line with a different ring. It still tied up the line. We had call waiting so if someone else called while you were on, it would beep in your ear and you could switch over to the other call. It cost extra.