Former journalist and goat farmer Peter Klages lives a life of tranquillity on his property in Campbelltown, 45 kilometres north of Ballarat.

But he is increasingly worried the upcoming nationwide closure of 3G networks will leave him completely isolated.

"[The reception] is very, very weak. It's been like that since I moved here. It fails over to 3G quite a lot," Mr Klages said.

"Apps like Facebook and Twitter are slow to load and very often pictures don't load."

Telstra and Optus have announced they will shut down their 3G networks on October 28. 

Vodafone has already switched off its 3G network. 

The move has been in planning since 2019, to boost the capacity, speed and reliability of 4G and 5G networks.

Mr Klages said he had regularly contacted Telstra about a lack of coverage and had monitored nearby mobile towers via an app for two years with no change in signal. 

He said he believed Telstra had no incentive to improve coverage in his region because there were few residents.

"The Postmaster General's Department put a manual phone in every household … that's why the old copper wire network is actually so extensive," he said.

"But since mobile phones … they go for critical mass [and] concentrate on the metropolitan areas, people who live in rural communities don't get a show."

'Every upgrade gets worse'

Kristine McMillan requires regular medical treatment for breast cancer at her 485-hectare Bulgana property, 20km north of Ararat.

But the lack of reception at her farm has her pondering whether she needs to sell up and move into town.

Despite having a 4G compatible handset, she said with "every upgrade, things get worse" and she needed to be able to contact her nurses if she required urgent treatment.

"If you were up in the paddock somewhere with no phone coverage, if you had a heart attack or something, I guess you just die until someone finds you," she said.

Ms McMillan's son installed an aerial on the roof of her house about four years ago to get a better signal, which cost $1,500.

The antenna points to a tower on nearby Mount Cole which Ms McMillan said had improved a 3G signal to her home slightly, but she was concerned about whether it would work beyond October.

Telstra and Optus have delayed their 3G shutdown date twice following concerns about a lack of public awareness.

They said the delay would give customers more time to check their devices were compatible with the 4G or 5G network, particularly for emergency calls. 

Lack of coverage will mean extra work

Nhill-based agronomist Marty Colbert drives across Australia for his job and uses large data files and drone imagery.

He said the 4G network had not been improved enough to cover the gaps that would be left when 3G was shutdown.

"I'm sure they can point to a few places where they have improved it, but it's nowhere I travel and, in my role, I travel not only across Victoria and South Australia but to most places of Australia," he said.

"[I] rely heavily on the ability to make phone calls and send and receive data to do with agronomy and it just hasn't been improved.

"So it makes me wonder about the validity of [Telstra's] statements that they've had independent reviews done."

Telstra said it had been conducting sample field testing and using sophisticated prediction tools to test coverage ahead of the shutdown. 

Regional general manager Chris Taylor said he was "very confident … that those predictions will hold up".

"The reason we are confident of that is our 4G network in regional areas is built on a lower frequency than the 3G network," he said. 

Has enough testing been done?

RMIT school of engineering Associate Professor Mark Gregory said neither customers or telcos would know the true extent of coverage until after the shutdown.

"I don't think at this stage that there's been enough testing done of the 4G network to safely and satisfactorily turn off the network [and] I think more work needs to be done," he said.

"I think it's wrong to put it back onto the customer to resolve issues."

Professor Gregory said the software used by telcos to predict what coverage would be like was leading to telcos "overstating what 4G will provide".

"It is one thing to make that argument in a laboratory, but it's a different matter in the real world," he said. 

"There's also the amount of data being made available into the network and we know in regional and remote Australia, that's a problem."

Professor Gregory said more work was still needed to boost connectivity, including introducing more mobile boosters, adjusting transmission on towers and utilising more power on those towers.

Telcos 'confident' of coverage 

Mr Taylor said Telstra was "very confident that most people currently able to make a handheld voice call on the 3G coverage will be able to do the same on the 4G network". 

Optus said its customers would benefit from the 3G closure.

"The 3G switch off will not remove coverage for customers. Our 4G network is larger than our 3G network," the spokesperson said. 

Anyone with equipment reliant on 3G coverage — including medical alarms and EFTPOS machines — is urged to contact their supplier and check if it will be compatible with 4G. 

Customers can check if their mobile is compatible with 4G by texting "3" to 3498.