[UPDATE: The problem persisted into the evening for some users, but was resolved overnight.]
Some 2degrees customers can't make voice calls after problems hit the company's landline broadband network earlier today.
One customer told the Herald the problems first hit around 7.15am.
As of midday, the problem persisted, with no estimated time for a fix.
The Herald understands Nelson Marlborough DHB and Christchurch City Council are among those affected.
"It's a calling and PBX issue for business customers at this stage," a 2degrees spokeswoman told the Herald.
"For some, we've been able to put in place a workaround while we fix the core issue.
"Other customers are having their calls diverted to mobile while we fix the issue as it relates to their technology."
In April, 2degrees joined its peers in announcing a drive to cut-costs. The restructure included laying off 120 people or around 10 per cent of its staff.
2degrees launched as a mobile-only carrier but entered the landline market in 2015 when it bought Snap Internet, and its 20,000 customers, for $28 million.
Accounts filed by its American parent, Toronto-listed Trilogy International Partners, show that, after a slow start, 2degrees' fixed-line business has pepped up over the past three years.
The telco had 32,000 fixed customers in 2018, 87,000 in 2019 and 115,000 as of the first quarter of 2020 (the company's calendar and financial years coincide).
That puts 2degrees neck-and-neck with Trustpower for fifth-place in fixed broadband in NZ, behind Orcon and Slingshot owner Vocus (225,000), Vodafone (just over 400,000) and Spark (just under 700,000).