The colloquial Australian-English phrase galah session designates a period allocated for private conversation, especially between women on isolated stations, over an outback radio network.

The noun galah designates a very common, small Australian cockatoo with a pink breast and grey back.

This noun is a borrowing from Yuwaalaraay * gilaa, and similar words in related languages of north-central and north-western New South Wales.

* Yuwaalaraay is a language of north-western New South Wales.

The earliest occurrences of the phrase galah session that I have found are as follows, in chronological order:

1-: From Aussie Doctors Tell of Hospital Plan “Down Under”, published in The Brantford Expositor (Brantford, Ontario, Canada) of Friday 16^th January 1948 [page 16, column 3]:

The Flying Doctor Service operates from a number of bases throughout Australia to ensure that no one, no matter how remote his home may be, is beyond the range of medical aid. Doctors are called from outlying settlements by radio for advice, and travel by air to give personal attention when required. The service is free and is maintained by Federal and State funds and philanthropic gifts.
[…]
The network was also used to relieve the loneliness of the outback. It was thrown open for general conversation, between women from 2 p.m. till 4 p.m. each day and between men from 7 p.m. till 8 p.m. It operated like a party line with everyone who cared, able to talk or listen and was known as the galah session. (The galah is a particularly noisy Australian cockatoo).

2-: From Value Of Flying Doctor Radio, a correspondence from Broken Hill, in New South Wales, published in The Sydney Morning Herald (Sydney, New South Wales, Australia) of Tuesday 15^th March 1949 [page 2, column 7]—the meaning of “wool holiday plans” is obscure:

Listening to the daily sessions, which virtually merged into one continuous session of over 12 hours daily during the worst of the floods, I glimpsed how this radio hook-up has widened and enriched with interest the lives of previously very lonely people.
Everyone with a set can hear what is going on, and after the sessions the people of the outback gossip freely among themselves by radio. It is the familiar yarn over the suburban back fence, but on the heroic scale, for hundreds of miles separate these neighbours. They freely exchange all the small talk of a community. Johnny’s fretfulness with the measles, the latest in frocks, the outlook for wool holiday plans, and tips on the destruction of the dingoes.
The menfolk call these informal talks “galah sessions,” a rather blunt way of saying that even in the outback the women do most of the talking, for the galah is a screeching chatterer.

3-: From They’re mining mica now—tomorrow it may be uranium, a correspondence from a mining camp in central Australia, by Betty Roland, published in The Herald (Melbourne, Victoria, Australia) of Saturday 4^th June 1949 [page 11, column 4]:

Since the coming of the transceiver, a variation of the wartime “walkie-talkie,” the lot of the outback dweller has undergone a remarkable change. Twice dally, when their particular circuit is on the air, they can communicate with the base at Alice Springs.
By this means, they can report an accident and have the Flying Doctor service set in operation inside the space of a few minutes, they can ask for help and advice in the case of sickness, hear what is taking place outside, and, last but not least, listen-in to the gossip of their neighbors; for it is possible to communicate with one another on what is a kind of glorified party-line in what is facetiously called “the galah session.”

The expression galah session has come to designate, by extension, any long chat.

The earliest occurrence of this transferred use that I have found is from a correspondence from Portugal, by Margaret Sydney, published in The Australian Women’s Weekly (Sydney, New South Wales, Australia) of Wednesday 19^th July 1967 [page 43, column 1]:

Everywhere on the roads you see women—women walking with that wonderful, upright carriage that allows them to carry huge bales of straw and firewood and baskets of fish and vegetables and great metal or pottery water-jugs on their heads; old women lifting their black skirts to sit on sun-warmed steps in village streets; groups of women making a galah-session of washing in the village streams; women ploughing and picking and digging, sometimes accompanied by bare-bottomed children.