Chorus has lost its appeal against the corporate regulator's decision, forcing it to slash its prices for broadband services, over copper wires.
In November last year, the Commerce Commission ruled that Chorus must halve the price of those services from the start of December to $10.92 a month.
Chorus had previously lost a High Court challenge to the commission's decision, which was based on benchmarking New Zealand against other countries including Sweden.
Chorus has argued that the commission erred in law and had failed to consider evidence of different New Zealand cost drivers that might have required a higher price.
A three-judge panel of the Court of Appeal has now also dismissed its case, saying the Commerce Commission made no error and exercised its judgement reasonably, based on facts.
Chorus refused an interview with Radio New Zealand but its general counsel, Vanessa Oakley, said in a statement that the company is disappointed but the ruling was not entirely unexpected.
Ms Oakley said the regulatory environment is completely out of kilter with the industry's structure and the effective delivery of government policy.
The commission is conducting a review of the actual costs of Chorus' copper wire services and expects to make a final decision by April next year.