A 600 series connector is an obsolete three-pin connector with up to six conductors.

It was for many years the standard telephone service connector in Australia, but has now been replaced by the six position modular connector in this application. As of 2008 a large installed base remained and a large variety of connectors, adapters and equipment such as ADSL filters were still in production and readily available.

It has no other common or standard use, either within Australia or beyond. However it is manufactured in other countries, usually in China, for export to Australia.

The 600 series plug has up to three flat pins plus a non-conducting spigot, which ensures correctly oriented insertion. Each pin carries up to two conductors by means of two contacts, one on each side of the pin. The pin bodies are of a non-conductive plastic material.