Editing 600 series connector (section)

==Varieties==

The original series 600 plugs and sockets were designed to be equally suitable for fixed wall mounting or for use on flexible cords. Such connectors are still available, but specialised fixed and line versions also exist.<ref>[https://www.accesscomms.com.au/australian-telecommunications-plugs-sockets/ Australian Telecommunications Plugs & Sockets] Access Telecommunications</ref>

===605 plug===

Standard three pin six conductor. Often now replaced by a modular 6P2C connector and an adaptor; In particular, this combination is now the most common connector supplied with new equipment in Australia.

The non-conducting spigot of the original 605 plug was provided with a hole for a countersunk screw, allowing the plug to be fixed in a wall-mounted socket. Removal then required first removing the socket cover, to allow this retaining screw to be removed. In this way a semi-permanent connection, requiring tools for disconnection, could be achieved.

===610 socket===

Standard six conductor.

The original 610 socket was provided with two mounting holes, one behind the receptacle for the plug spigot, and both for countersunk screws. This arrangement allowed the socket to be secured using two screws, with no plug inserted, or alternatively with the plug inserted, using the same two mounting holes but with one of the screws passing through the spigot to secure the plug as well.

===611 socket===

Similar to 610, but with the contacts of pairs one and two allowed to connect when no plug is inserted, contact 1 connecting to 2 and 5 to 6.

This is particularly designed for [[mode 3 (telephone)|mode 3]] connection. The incoming line to the mode 3 device is connected using pair one, and pair two is used as the outgoing line to other devices. If the mode 3 device is unplugged, the switch contacts maintain line connection to the other devices.

This function is not generally supported by modular connectors. Modular connectors providing suitable switch contacts are available but not common; Instead, mode 3 devices use two modular connectors, one for the incoming line and the other for the outgoing line. The convenience of using a single connector in this application is one reason for the continued use of 600 series connectors, but mixing this wiring scheme with modular connectors does not work well. 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.

Many recent 611 sockets have a stepped recess for the plug spigot, to accept a plug with a larger spigot but still provide a good fit for a standard 605 plug. Equipment requiring mode 3 connection can then be equipped with these larger spigot plugs, to prevent this equipment being connected to a 610 socket which does not provide mode 3 support. These plugs are common on older fax machines and modems, and used on some security and similar equipment. These plugs were also used on [[Telex]] machines within Australia.

===Other varieties===

====60x plugs====

In general, 60x where x is any numeric other than 0 or 5 indicates a non-standard plug. Compatibility and designs vary from maker to maker.

====61x sockets====

In general, 61x where x is any numeric other than 0 or 1 indicates a non-standard socket. Compatibility and designs vary from maker to maker.

====Extensions====

Extension leads are generally four conductor, including pair one and one other pair, wired straight through pin to pin. Some incorporate an adaptor plug which includes a 610 socket, often with all six conductors connected, allowing the extension to also serve as a double adaptor.

====Double adaptors====

Double adaptors are almost always six conductor, wired pin to pin, with a 605 plug and two 610 sockets in parallel.

====Mode 3 adaptors====

A mode 3 adaptor appears physically to be a double adaptor, but the sockets are one 610 and one 611, with pair one of the 610 wired to pair two of the 611, and pair one of the 611 to pair one of the plug. Treatment of the other conductors varies, and may be assignable.