According to these figures, 64% of Australians had a fixed-line telephone service at home in 2016-17, a statement from Finder said.
The website plotted a graph for the figures, using the same rate of decline as in previous years and by 2037 the percentage was -1%.
Finder's claim comes at a time when British Telecom has reiterated its move to get rid of its PSTN network in favour of VoIP systems by 2025, a decision which was initially announced in 2017.
Finder cited 2017 statistics it had collected from 2005 respondents showing that 29% of Australians had a landline that was regularly used and the majority of these were older.
Kidman tied the decrease in landlines to the increasing take-up of connections to the national broadband network.
Finder claimed many Australians had retained landlines to contact relatives overseas but said that this had now become cheaper through apps like Skype and WhatsApp.
Additionally, there are a number of SIMs on offer which make calling other countries very cheap.