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In 20th century telephone systems, a party line (also multiparty line or Shared Service Line) is an arrangement in which two or more customers are connected directly to the same local loop. Prior to World War II in the United States, party lines were the primary way residential subscribers acquired local phone service. British users similarly benefited from the party line discount.
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Selective ring
Originally, in order to distinguish one line subscriber from another, operators developed different ringing cadences for the subscribers so that if the call was for the first subscriber to the line, the ring would follow one pattern such as two short rings, if the call was for the second subscriber, the ring would sound another way, such as a short ring followed by a long one, and so on. Other subscribers on the line heard the ring and might listen in. [1] Frequently ringing phones were an annoyance, so selective ringing methods were introduced in the mid 20th century. Especially effective on two-party lines was the distinction between tip party and ring party. Each telephone bell, rather than being connected across tip and ring as usual, was connected from one wire to local ground. Thus only the selected station in a two party line would ring. For multiparty lines all the "tip parties" or all the "ring parties" would ring, in this semiselective scheme.
Later systems applied multiple ringing frequencies for fully selective ringing. Equipment at an individual subscriber's location could distinguish several different ringing signals so that only the desired party's phone would actually ring. In this arrangement the only inconvenience of a party line was occasionally finding the line in use (by hearing talking) when one picked up the phone to make a call. If one of the parties used the phone heavily then the inconvenience for the others was more than occasional.
Characteristics of party lines
- With party line service, it was usually necessary to complete a long distance call through the operator to identify and correctly bill the calling party.
- When the party line is already in use, if any of the other subscribers to that line pick up the phone, they can hear and participate in the conversation. Eavesdropping opportunities abounded, as shown in the 1959 film Pillow Talk.
- The completely non-private party lines were a cultural fixture of rural areas for many decades, and were frequently used as a source of entertainment and gossip, as well as a means of quickly alerting entire neighbourhoods in case of emergencies such as fires.
- Party lines remain primarily in rural areas where local loops are long and private loops uneconomical when spread sparsely over a large area. Privacy is limited and congestion often occurs. In isolated communities, party lines have been used without any direct connection to the outside world.
- Party lines are not suitable for Internet access. If one customer is using dial up, it will jam the line for every customer. Bridge taps make party lines unsuitable for DSL.
Use on railways
Party line usage was at one time common on railways, where numerous telephones were connected to a single pair of wires. Usually a long ring of many turns of the handle would alert the exchange that a connection was required to another destination. The problem of selective calling was also solved by a mechanical device which could selectively ring one or a group of stations.
Party lines still in existence
One example of a community linked by party line is Adams' Pack Station, high in the mountains above Los Angeles. Big Santa Anita Canyon, near Sierra Madre, CA, has 81 rustic cabins, a group camp and a pack station that all communicate by magneto-type crank phones. One ring is for the pack station, two rings for the camp and three rings means all cabins pick up.[2]
References
- ^ [1]"Electricity and Magnetism; Principles of Telephony; Subscribers' Station ..." By International Correspondence Schools,1916, page 20. Retrieved May 27,2008
- ^ Adams' Pack Station - Chantry Flat, Ca
