<P> In 1956, Southern Bell officials refused a request from a public utilities commissioner in Jackson, Mississippi to segregate party telephone lines on racial boundaries . </P> <P> While primitive lockout devices to prevent two subscribers from picking up the same line at the same time were proposed relatively early, multiple simultaneous calls did not become viable until the initial tests of transistorised pair gain devices in 1955 . Any handset off - hook therefore tied up the line for everyone . </P> <P> Many jurisdictions require a person engaged in a call on a party line to end the call immediately if another party needs the line for an emergency . Such laws also provide penalties for abuse by falsifying emergency situations . In May 1955, a Rhinebeck, New York woman was indicted by a grand jury after her refusal to relinquish a party line delayed a volunteer firefighter's effort to report a grass fire; the fire destroyed a shed and a barn . She was given a suspended sentence . In June 1970, a sixteen - year - old girl and a woman were charged after refusing to relinquish a party line to allow a distress call as three boys drowned in a pond in Walsenburg, Colorado . </P> <P> By the 1980s, party lines were displaced in most localities as they could not support subscriber - owned equipment such as answering machines and computer modems . The electro - mechanical switching equipment required for their operation was rapidly becoming obsolete, supplanted by electronic and digital switching equipment . The new telephone exchange equipment offered vertical service code calling features such as call forwarding and call waiting, but often was incompatible with multi-party lines . </P>

When did they get rid of party lines