"Kia ora, tolls here."

The simple act of answering the phone with the now widely-used Māori greeting nearly lost Dame Naida Glavish her job 40 years ago.

Glavish, then known as Naida Povey, had used the greeting since starting her work as a toll operator in 1975, but a promotion to a senior role in Auckland and the arrival of a new supervisor from Taupō who stuck "strictly" to the rules saw the "challenges begin", she said.

"The rules were 'good morning', 'good afternoon', 'good evening'.

"Whether it was morning, afternoon or evening, 'kia ora' was appropriate, and so I continued to say 'kia ora', which led them, of course, to placing me on off-board positions."

Attending a tangi up north for her auntie which was later extended with the death of her cousin, Glavish was returning to Auckland when she considered "easing off" and giving her supervisor a break.

"As I said that to myself, only me in the car, this voice came in my ear, 'Nui ake tēnei take i a koe' – 'this is far greater than just you'.

"I knew that this was the voice of my grandmother reminding me of who I am."

Marching into her supervisor's office, Glavish told him: "I will respect and accept what you have to do as a supervisor, the same as I will ask you to accept what will do as I have to do as the mokopuna of my grandmother."

Not long after, Glavish was front-page news.

"It just happened so quickly. So much so that schools were writing in, and Air New Zealand began greeting passengers with 'kia ora'."

Postmaster-General Rob Talbot initially supported the ban on 'kia ora'.

"I hope that Mrs Povey will fit into the good will and need to have the efficient running of the toll rooms as they have in the past and not make a mountain out of a mole hill on this issue," he said at the time.

However, he changed his mind, later convincing then Prime Minister Robert Muldoon to make a statement.

"He said, 'I've been overseas deciding the economics of this country and I get back here and some girl wants to say 'kia ora'," Glavish recalled.

"Well as far as I'm concerned, she can say 'kia ora', as long as she doesn't want to say 'g'day blue' – and with that, it was over."

Suddenly, the woman they had tried to hide was the star of the toll room.

Glavish remembered being put on 12am-6am shifts because the volume of calls coming in to speak to the "kia ora lady" was jamming the system.

It would become a key moment in the revitalisation of te reo Māori, with the language made an official one in 1987, and a New Zealand tourism campaign using "kia ora" as a cornerstone in the mid-'90s.

"As far as I'm concerned, I fought the battle, but it was the country that won the war," Glavish said.

Asked what hearing te reo Māori today is like, Glavish said it "fills her heart".

"It lives on when we hear, it lives on when we see it, it lives on when we speak it. It warms the body, the mind, and the spirit."