[broadgage]

There was another system, sometimes incorrectly called a party line, but more properly known as a "call concentrator"

Consider a village with 6 telephone subscribers and connected to the distant exchange by a cable or overhead line route with 10 circuits so as to allow for expansion.
In time, more than 10 telephone lines might be required. To avoid costly replacement of the existing cables, a concentrator could be installed. This was in effect a miniature and fully automatic exchange that connected one of the 10 existing lines to whichever telephone was in use.
This allowed the existing 10 lines to serve several times that number of customers, provided that only 10 of these customers used the phone at the same time.
If two subscribers WITHIN the village wished to talk, the concentrator would connect them to each other without use of any of the ten lines to the distant exchange.
The equipment was often installed in a secure cabinet, in the village public phone box.