Lines company Chorus plans to retire the copper network within the next decade and become an all-fibre company.
The company said the move was in line with consumer behaviour and the increasing coverage fibre and alternative technologies could offer in rural areas.
Chief executive JB Rousselot said fibre uptake had exceeded 70 percent where it was available, whereas copper was serving a market that was a fraction of its original size.
"As superior alternative technologies emerge, we see that copper will not be sustainable or suitable to meet New Zealanders' growing connectivity needs," he said.
"Our goal is to have customers on the best technology available to them, and copper is no longer that solution, particularly in more remote rural areas."
Rousselot said the group would work with industry and government to ensure those unable to access fibre broadband would still have connectivity as the copper network was retired.
"We believe providing this clarity now will ensure that further investment in this critical part of New Zealand's connectivity will focus on the right solutions for our rural communities," he said.
He estimated about $500 million of investment could extend the company's fibre network to another 75,000 premises, providing more than 90 percent of the population access to fibre.