Party line (telephony)

A party line (multiparty line, shared service line, party wire) is a local loop telephone circuit that is shared by multiple telephone service subscribers.

Party line systems were widely used to provide telephone service, starting with the first commercial switchboards in 1878. A majority of Bell System subscribers in the mid-20th century in the United States and Canada were serviced by party lines, which carried a billing discount over individual service; during wartime shortages, these were often the only available lines. British users similarly benefited from the party line discount. Farmers in rural Australia used party lines, where a single line spanned miles from the nearest town to one property and on to the next.

Telephone companies offered party lines since the late 1800s, although subscribers in all but the most rural areas may have had the option to upgrade to private line service at an additional monthly charge. The service was common in sparsely-populated areas where remote properties are spread across large distances, such as Australia (where these were operated by the Government Post Master General department). In rural areas in the early 20th century, additional subscribers and telephones, often numbered in several dozen, were frequently connected to the single loop available.

Party lines provided no privacy in communication. They were frequently used as a source of entertainment and gossip, as well as a means of quickly alerting entire neighbourhoods of emergencies such as fires, becoming a cultural fixture of rural areas for many decades.

The rapid growth of telephone service demand, especially after World War II, resulted in a large fraction of party line installations in the middle of the 20th century in the United States. This often led to traffic congestion in the telephone network, as the line to a destination telephone was often busy. Nearly three-quarters of Pennsylvania residential service in 1943 was party line, with users encouraged to limit calls to five minutes. Shortages persisted for years after each war; private lines in Montreal remained in short supply at the end of 1919 and similar shortages were reported by telephone companies in Florida as late as 1948, Some rural users had to run their own wires to reach the utility's lines.

Objections about one party monopolizing a multi-party line were a staple of complaints to telephone companies and letters to advice columnists for years and eavesdropping on calls remained an ongoing concern.

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