600 series connector

It was for many years the standard telephone service connector in Australia, used on rural party lines and the national Postmaster-General's Department (later Telstra) landline network, but has since the 1970s been superseded by the six position modular connector in this application.

The 600 series plug has up to three flat pins plus a non-conducting spigot, which ensures correctly oriented insertion.

The original series 600 plugs and sockets were designed to be equally suitable for fixed wall mounting or for use on flexible cords.

The original 610 socket was provided with two mounting holes, one behind the receptacle for the plug spigot, and both for countersunk screws.

For example, if a modern modem with its supplied 6P2C adaptor is plugged into a conventionally wired 611 mode 3 socket, the result is to disconnect all downstream devices.

In some sockets conductors 3 and 4 also connect when no plug is present, shorting pair three.

Sockets are also available with cams to allow the switching functions to be selectively enabled as required.

In some older sockets this could be achieved by simply bending the contacts; The cams merely implement this useful accidental feature in an intentional fashion.

These plugs are common on older fax machines and modems, and used on some security and similar equipment.

The contact terminals are normally labelled with their numbers on rewireable plugs and sockets.

This was to avoid a bell tinkling noise during dialling, from any on-hook phones in the circuit.

Electro-mechanical phones such as the 800 series had their internal wiring slightly adjusted to support such multiple extension use.

Equipment such as handsets, modems and extension bells sold in or for use in Australia often arrives packaged with one of these adaptors.