But they're still sitting there on street corners and in airports across the country, waiting forlornly for someone to drop in 50 cents and make a call.

The public payphone, once an integral part of staying connected to the outside world, remains in existence but is on life support and becoming increasingly endangered.

The number of payphones across Australia has more than halved in the past decade, from almost 70,000 a decade ago to less than 30,000 last year.

In the early 1990s, at the end of the payphone's glory days before mobile phones reached saturation point, there were more than 80,000.

At the same time as payphone numbers have crashed, mobile phone use has exploded.

Figures from the Australian Communications and Media Authority show there were more than 31 million mobile services in use last year.

With smartphones just about everywhere, it might be surprising that there are payphones on the streets at all. But people are still using them, if only in a back-up capacity.

ACMA's research shows 9 per cent of people used a payphone in the six months to May last year.

Australian Communications Consumer Action Network chief executive Teresa Corbin said payphones remained an important service, particularly to those on low income or in rural areas.

Telstra is still the main provider of payphones, along with private operators which supply them to shopping centres, casinos and airports.

"The social impact needs to be carefully assessed and taken into account, and broad community consultation occur, before payphones are removed," she said.

Dr Bruce Redman of the Salvation Army said it was important for those doing it tough to stay connected, whether it's with their family or other networks.

He said the Salvos might need to rethink their practice of handing out phone cards if payphones become harder to find.

And while recent research by the University of Sydney showed the homeless are big users of mobile phones, Dr Redman said it was often a struggle to keep them topped up with credit.

"Community is a really big part of maintaining a positive sense of mental health," he said.

Having a payphone close by in an emergency can also be important. Mobile phones are often plagued by battery problems, lack of credit or simply being out of service.

And it's not just for calling a tow truck during a car breakdown. ACMA said 2.4 per cent of all calls to emergency services last year were made from public payphones.

But despite the rapid rate of its decline and our heavy reliance on mobile phones, the payphone's future does look secure.

Last year, Telstra signed a 20-year contract with the government worth $40 million a year to maintain its collection of payphones.

There have also been moves in New York, London and New Zealand to convert payphone booths into Wi-Fi hotspots which can be used by smartphones.

It's an engaging story, the payphone of the future could become a tool of the very thing that nearly killed it.