Communications Minister Mitch Fifield said in a statement that the decision would ensure certainty for people, particularly those in remote and rural areas.
Over 12 months of study, the government said research had "shown that while savings could be made in the delivery of voice services using new technologies in rural and remote areas, moving away from the existing copper and wireless networks in NBN Co's fixed wireless and satellite areas, at this time, would create concerns for rural and remote customers and counter‑balance costs for NBN Co".
A report summarising the work was released on Wednesday.
Telstra payphones that service Indigenous communities and those where there was no mobile coverage would generally be quarantined.
“We have listened to regional Australians and heard the importance of maintaining existing copper and wireless networks for fixed voice calls in NBN Co's fixed wireless and satellite areas," he said.
"I thank everyone who took the time to provide their views on this critical issue.
“We will not make changes that affect regional Australians until there are robust and proven alternatives to the existing USO.”
The statement said the government would deliver the broadband part of the USG through the national broadband network, and that more than 98% of premises outside major urban areas could now order an NBN service or had construction underway.
Reacting to the announcement, Labor Shadow Communications Minister Michelle Rowland and Shadow Minister for Regional Communications Stephen Jones said: "Following a Productivity Commission review which commenced in June 2016, a USO taskforce, and 2½ years having elapsed, Mitch Fifield has today re-announced an acronym to describe existing safeguards for the delivery of phone and broadband services.
"NBN Co already has a universal service delivery obligation for broadband via its Statement of Expectations, and Telstra has a USO obligation for delivery of voice services.
"Coming up with a new acronym – the Universal Service Guarantee (USG) — to describe what is already there does not constitute progress.
"The government has also failed to offer any views on the future relationship between the USO levy and its proposed regional broadband levy.
"This latest development is simply an in-tray clearing exercise by a Minister who has given up on governing."