The first phone number that we had when I was a kid (in the '50's) was PArkway 7814. You only dialed the letters PA, which represented 72. So numerically our number was 72-7814. Only six digits. And it was in a moderately big city. We were on a "two party line" which meant that while you had a unique number dialing in, you were actually sharing the line with someone else. So if you lifted the handset and heard someone else talking, you quietly put the phone down and waited a while. When I was 7 or 8, they added a digit, so our number became PA2-7814. A few years later my folks "splurged" and got us a "private" line.
In the rural areas, sometimes farmers would have 8 or 16-party lines. I think that most of those were on really old phones without a dial, so you lifted the earpiece, and waited for the operator. When you were getting an incoming call, each home would have a distinctive ring. Like "two longs and one short". I remember being told that when the doctor or minister was called (people learned the ring pattern of those people) late at night, that so many people might listen in that it was hard to hear what was being said.