Three short rings signified the call was for the party with the S letter and so on.
To signal specific subscribers on party lines selectively, telephone operating companies implemented various signaling systems.
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.
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 numbering several dozen, were frequently connected to the single loop available. 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.
Illinois State University terminated its last party line in 1990.
One of the last manual telephone exchanges with party lines in Australia was closed down in 1986 in the township of Collarenebri, where most town residents had a telephone number of only three digits, and to make a call outside the exchange area it was necessary to call the exchange to place a call.
For though one was only to answer one's own ringing code, every party on the same subscriber line could hear all the ringing codes.