Editing 600 series connector (section)

====Wiring detail and explanation====
{{unreferenced section|date=May 2020}}
In the early 1980s [[Telstra|Telecom]] would install multiple phone sockets in premises as requested, but charged a rental fee per socket, to cover installation and maintenance. In this era the ringing tone was generated by electro-mechanical bells in each phone and with pulse dialling then in use, the 6xx series plugs and sockets supported separation of the bell circuit. This was to avoid a bell tinkling noise during dialling, from any on-hook phones in the circuit. The standard multi-extension wiring in residential premises thus used 3 wires of the 4 wire cable. White was wired to pins 2 and 3 which were bridged by a link in each socket. Red (bell circuit) was connect to pin 5 and blue was connected to pin 6. The black wire was unused and left unconnected in the socket. Electro-mechanical phones such as the 800 series had their internal wiring slightly adjusted to support such multiple extension use.

When phones moved to electronic ringers and tone dialling, the additional socket wiring using pins 3 and 5 was no longer needed for suppression and the use of only pair one, with white on pin 2 and blue on pin 6 became the standard socket wiring, until being superseded by the modular connector.