You remember party lines.
They still have those in some of the more remote areas, I went to a friend's lake house deep in the Adirondacks last summer and they had a party line across 5 houses.
Every now and then, when the phone trunk line gets old or damaged, multiple conductors will get shorted together, or if they're working on something, my land line at home will temporarily become a party line. It's annoying as hell, and is one of the main reasons I jumped onto the VOIP bandwagon the second it became available.