page_title: Party line (telephony)
section_title: Selective ringing
hierarchical_section_title: Party line (telephony) / Selective ringing
caption_attribution_description: English: Advertisement advising party line subscribers to be courteous about their shared telephone line
context_page_description: A party line 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 and South Africa used party lines, where a single line spanned miles from the nearest town to one property and on to the next.
context_section_description: To signal specific subscribers on party lines selectively, telephone operating companies implemented various signaling systems.
  The earliest selective system was the code ringing system, in which each telephone subscriber was assigned a specific ringing cadence, (not to be confused with modern ring tones).
  Although various systems were implemented, one that limited the number of coded rings but established a uniform and readily understood format, was to first give the subscriber number as individual digits, which could be from one to four digits long per exchange,
  separated by the instructional word "ring" followed by the two digits of the ring code where the first digit indicated the number of long rings, followed by the second digit indicating the number of short rings.  Thus spoken, for example, as "nine, three; ring two, two" to mean subscriber No. 93 with ringing code 2 long and 2 short, and written as "93R22", (and if outside the given exchange, then the exchange would be asked for by name before the requested number and ringing code, e.g. "Rockridge nine, three; ring one, two" i.e. "(On the) Rockridge (exchange), (subscriber No.) nine, three; ring one long, and two short," and written as “Rockridge 93R12”.  (The two examples cited in this paragraph are taken directly from usage in the 1935 American film Party Wire.)  Whilst this practice was common, it was not ubiquitous, since despite giving a standard configuration for terse, easily interpreted numbers with their respective ring codes, its chief functional drawback was with the first ring always being long and the second always being short, which limited the number of brief and thus practical ringing combinations that could be used on single multiparty subscriber numbers.
  Further to this functional deficiency, was a twofold practical deficiency. 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.  This meant firstly, frequently ringing telephones were a disruptive annoyance, as each party on the line had to stop to listen every time the telephone rang in order to determine according to the ringing cadence if they were the party being called on any given ring. Secondly, if any party on a given line should so be inclined, there was the insidious opportunity to listen in on other parties' calls.
  More selective ringing methods were introduced using various technologies.
  In the system of divided ringing, the ringing circuit was separated from the talking circuit by adding a ground connection between the central office and the subscriber stations for ringing. On the same subscriber line, one party used the tip side of the line and ground for ringing, whilst the other party on the same line used the ring wire and ground for ringing, to achieve full selectivity for two-party lines, in which only the selected station would ring.  These names for the wires are derived from the paired cord plugs—used on a manual switchboard—composed of three parts: the tip and the sleeve separated by a narrow metal band called the ring, each of these three components being insulated from one another.  
  In the Bell System, the two stations were thus called the tip party and the ring party, In combination with code ringing, this method could be extended to four and eight subscribers to reduce the number of disturbances. In several variations of divided ringing, also called grounded ringing, the bells were activated with polarized current, so that full selectivity was achieved for up to four parties.
  Another selective ringing system was based on using different ringing frequencies for each station on the party line. In North America, this was used mostly by independent telephone systems, while the Bell System abandoned frequency selective ringing in the early 1900s. Initially four frequencies were used, which were based on a system of harmonic multiples of a frequency of 16 2/3 Hz. Combined with divided ringing, this provided fully selective service for up to eight stations.
  All fully selective ringing systems on 
caption: As upgrades made party-lines more popular in the 1940s, local telephone companies ran frequent ads to instill community spirit and personal courtesy in party-line subscribers.
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