Adult party phone chat
For rural residents, many were on a single telephone line identified by a number and a property name, such as "Gundabluie 1".
Each party on that single line was identified by a letter, and the ringing pattern for that party would consist of the corresponding letter in Morse code.
In June 1968, the conviction of three Winter Park, Florida men on bookmaking charges was overturned as police had used a party-line telephone in a rented house on the same line as the suspects to unlawfully intercept their communications.
Any handset off-hook therefore tied up the line for everyone.
The service was common in sparsely populated areas where remote properties were spread across large distances.
An example is Australia where these were operated by the Government Postmaster General's Department.
They could not support new technologies and subscriber-owned equipment such as answering machines and computer modems.
Meanwhile, the electro-mechanical switching equipment required for their operation was rapidly becoming obsolete, supplanted by electronic and digital switching equipment.
By the 1980s, party lines were removed in most localities.
This distinctive ring would alert all parties on the line who the call was for.